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- #!/usr/bin/ruby
- # Least Lucas number with n Lucas divisors
- # https://oeis.org/A356123
- # Known terms:
- # 1, 2, 4, 18, 1364, 1860498, 2537720636, 6440026026380244498, 8784200221406821330636, 77162173529763648886126034136172445632164498
- include("../../../factordb/auto.sf")
- var table = Hash()
- for k in (1..1e6) {
- var t = divisors(k.lucas).count{.is_lucas}
- if (!table.has(t)) {
- table{t} = k
- say("a(#{t}) = #{k.lucas}")
- }
- }
- __END__
- a(1) = 1
- a(2) = 3
- a(3) = 4
- a(4) = 18
- a(5) = 1364
- a(6) = 1860498
- a(7) = 2537720636
- a(8) = 6440026026380244498
- a(9) = 8784200221406821330636
- a(10) = 77162173529763648886126034136172445632164498
- a(13) = 677807981804381412733419097483256033462649109976189806684020291364
- a(11) = 4365101043708483494615466932242949707161871659736799144058331102381689400753867700636
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