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- #!/usr/bin/ruby
- # Composite numbers k where records occur for:
- #
- # lcm(gcd(k-1, lcm({p-1})), gcd(k+1, lcm({p+1})))
- #
- # where p are prime factors dividing k.
- var max = 0
- for k in (1..1e9) {
- k.is_composite || next
- var f = k.factor
- var g = lcm(gcd(k-1, f.lcm{.dec}), gcd(k+1, f.lcm{.inc}))
- if (g > max) {
- max = g
- print(k, ", ")
- }
- }
- __END__
- 4, 8, 15, 35, 63, 343, 377, 559, 1023, 1025, 8911, 16511, 25345, 139231, 1084159, 1556479,
- 4, 8, 9, 15, 35, 119, 195, 209, 231, 286, 377, 1105, 2015, 2465, 5719, 8695, 9879, 19669, 22359, 25345, 75701, 139231,
- 4, 8, 15, 35, 104, 119, 195, 209, 231, 286, 1105, 2015, 2465, 5719, 8695, 9879, 19669, 22359, 25345, 75701, 139231,
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