(In reply to
Solution by Jer)
63245986 is F39, not F52.
F52 = 32951280099 = 3 * 233 * 521 * 90481
Its presence of a factor of 521 prevents its having a GCD of 233 with F26 but it does have such with both F13 and F39.
13 233
26 121393
39 63245986
52 32951280099
233 121393
233 63245986
233 32951280099
121393 63245986
63245986 32951280099
a = 1: b = 1: c = 2
Do
d = b + c
a = b: b = c: c = d
ct = ct + 1
fib(ct) = d
q = Int(d / 233): r = q * 233  d
If r = 0 Then Text1.Text = Text1.Text & ct + 3 & Str(d) & crlf
Loop Until ct = 100 Or d > 10000000000000#
Text1.Text = Text1.Text & crlf
For i = 1 To ct  1
For j = i + 1 To ct
If gcd(fib(i), fib(j)) = 233 Then Text1.Text = Text1.Text & fib(i) & Str(fib(j)) & crlf
Next
Next
Function gcd(a, b)
x = a: y = b
Do
q = Int(x / y)
z = x  q * y
x = y: y = z
Loop Until z = 0
gcd = x
End Function
Edited on February 19, 2019, 11:24 am

Posted by Charlie
on 20190219 11:06:49 