' Generates Simple Magic Squares of order 4
' Based on Twin Pairs

' Tested with Office 2007 under Windows 7

```Sub Priem4d()

Dim a1(1172), a(32), b1(23967), b(23967), c(32)

y = MsgBox("Locked", vbCritical, "Routine Priem4d")
End

n2 = 0: n3 = 0: n9 = 0: n10 = 0: k1 = 1: k2 = 1

t1 = Timer

'   Applicable Range for Smaller Squares

Erase b1
For i1 = 1 To 96
x = Sheets("Priem").Cells(i1, 1).Value
a1(i1) = x
b1(x) = x
Next i1

m1 = 1: m2 = 96

For j100 = 204 To 420 Step 6
s1 = j100

'   Generate squares

a(17) = 2: n10 = 0

For j16 = m1 To m2                                          'a(16)
If b1(a1(j16)) = 0 Then GoTo 160
If b(a1(j16)) = 0 Then b(a1(j16)) = a1(j16): c(16) = a1(j16) Else GoTo 160
a(16) = a1(j16)

a(5) = a(16) - a(17)
If a(5) < a1(m1) Or a(5) > a1(m2) Then GoTo 50
If b1(a(5)) = 0 Then GoTo 50
If b(a(5)) = 0 Then b(a(5)) = a(5): c(5) = a(5) Else GoTo 50

For j15 = m1 To m2                                          'a(15)
If b1(a1(j15)) = 0 Then GoTo 150
If b(a1(j15)) = 0 Then b(a1(j15)) = a1(j15): c(15) = a1(j15) Else GoTo 150
a(15) = a1(j15)

a(6) = a(15) - a(17)
If a(6) < a1(m1) Or a(6) > a1(m2) Then GoTo 60
If b1(a(6)) = 0 Then GoTo 60
If b(a(6)) = 0 Then b(a(6)) = a(6): c(6) = a(6) Else GoTo 60

For j14 = m1 To m2                                          'a(14)
If b1(a1(j14)) = 0 Then GoTo 140
If b(a1(j14)) = 0 Then b(a1(j14)) = a1(j14): c(14) = a1(j14) Else GoTo 140
a(14) = a1(j14)

a(13) = s1 - a(14) - a(15) - a(16)
If a(13) < a1(m1) Or a(13) > a1(m2) Then GoTo 130
If b1(a(13)) = 0 Then GoTo 130
If b(a(13)) = 0 Then b(a(13)) = a(13): c(13) = a(13) Else GoTo 130

a(8) = s1 - a(14) - a(15) - a(16) + a(17)
If a(8) < a1(m1) Or a(8) > a1(m2) Then GoTo 80
If b1(a(8)) = 0 Then GoTo 80
If b(a(8)) = 0 Then b(a(8)) = a(8): c(8) = a(8) Else GoTo 80

a(7) = a(14) + a(17)
If a(7) < a1(m1) Or a(7) > a1(m2) Then GoTo 70
If b1(a(7)) = 0 Then GoTo 70
If b(a(7)) = 0 Then b(a(7)) = a(7): c(7) = a(7) Else GoTo 70

For j12 = m1 To m2                                          'a(12)
If b(a1(j12)) = 0 Then b(a1(j12)) = a1(j12): c(12) = a1(j12) Else GoTo 120
a(12) = a1(j12)

a(11) = s1 - a(12) - a(15) - a(16)
If a(11) < a1(m1) Or a(11) > a1(m2) Then GoTo 110
If b1(a(11)) = 0 Then GoTo 110
If b(a(11)) = 0 Then b(a(11)) = a(11): c(11) = a(11) Else GoTo 110

a(10) = a(12) - a(14) + a(16)
If a(10) < a1(m1) Or a(10) > a1(m2) Then GoTo 100
If b1(a(10)) = 0 Then GoTo 100
If b(a(10)) = 0 Then b(a(10)) = a(10): c(10) = a(10) Else GoTo 100

a(9) = -a(12) + a(14) + a(15)
If a(9) < a1(m1) Or a(9) > a1(m2) Then GoTo 90
If b1(a(9)) = 0 Then GoTo 90
If b(a(9)) = 0 Then b(a(9)) = a(9): c(9) = a(9) Else GoTo 90

a(4) = -a(12) + a(14) + a(15) - a(17)
If a(4) < a1(m1) Or a(4) > a1(m2) Then GoTo 40
If b1(a(4)) = 0 Then GoTo 40
If b(a(4)) = 0 Then b(a(4)) = a(4): c(4) = a(4) Else GoTo 40

a(3) = a(12) - a(14) + a(16) - a(17)
If a(3) < a1(m1) Or a(3) > a1(m2) Then GoTo 30
If b1(a(3)) = 0 Then GoTo 30
If b(a(3)) = 0 Then b(a(3)) = a(3): c(3) = a(3) Else GoTo 30

a(2) = s1 - a(12) - a(15) - a(16) + a(17)
If a(2) < a1(m1) Or a(2) > a1(m2) Then GoTo 20
If b1(a(2)) = 0 Then GoTo 20
If b(a(2)) = 0 Then b(a(2)) = a(2): c(2) = a(2) Else GoTo 20

a(1) = a(12) + a(17)
If a(1) < a1(m1) Or a(1) > a1(m2) Then GoTo 10
If b1(a(1)) = 0 Then GoTo 10
If b(a(1)) = 0 Then b(a(1)) = a(1): c(1) = a(1) Else GoTo 10

'                           Exclude solutions with identical numbers (Back Check)

'                           GoSub 800: If fl1 = 0 Then GoTo 5

n10 = n10 + 1
'                           n9 = n9 + 1: GoSub 640 'Print results (selected numbers)
n9 = n9 + 1: GoSub 650 'Print results (squares)
Erase b, c: GoTo 1000  'Print only first square

5

b(c(1)) = 0: c(1) = 0
10  b(c(2)) = 0: c(2) = 0
20  b(c(3)) = 0: c(3) = 0
30  b(c(4)) = 0: c(4) = 0
40  b(c(9)) = 0: c(9) = 0
90  b(c(10)) = 0: c(10) = 0
100 b(c(11)) = 0: c(11) = 0
110 b(c(12)) = 0: c(12) = 0
120 Next j12

b(c(7)) = 0: c(7) = 0
70  b(c(8)) = 0: c(8) = 0
80  b(c(13)) = 0: c(13) = 0
130 b(c(14)) = 0: c(14) = 0
140 Next j14

b(c(6)) = 0: c(6) = 0
60  b(c(15)) = 0: c(15) = 0
150 Next j15

b(c(5)) = 0: c(5) = 0
50  b(c(16)) = 0: c(16) = 0
160 Next j16

n10 = 0
1000  Next j100

t2 = Timer

t10 = Str(t2 - t1) + " sec., " + Str(n9) + " Solutions for sum" + Str(s1)
y = MsgBox(t10, 0, "Routine Priem4d")

End

'   Print results (selected numbers)

640 For i1 = 1 To 16
Cells(n9, i1).Value = a(i1)
Next i1

Return

'   Print results (squares)

650 n2 = n2 + 1
If n2 = 5 Then
n2 = 1: k1 = k1 + 5: k2 = 1
Else
If n9 > 1 Then k2 = k2 + 5
End If

Cells(k1, k2 + 1).Select
Cells(k1, k2 + 1).Font.Color = -4165632
Cells(k1, k2 + 1).Value = CStr(s1)

i3 = 0
For i1 = 1 To 4
For i2 = 1 To 4
i3 = i3 + 1
Cells(k1 + i1, k2 + i2).Value = a(i3)
Next i2
Next i1

Return

'   Exclude solutions with identical numbers

800 fl1 = 1
For j1 = 1 To 16
a2 = a(j1)
For j2 = (1 + j1) To 16
If a2 = a(j2) Then fl1 = 0: Return
Next j2
Next j1
Return

End Sub
```