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- #!/usr/bin/ruby
- # a(n) is the smallest k such that psi(k) = n!, or 0 if no such k exists (psi(k) = A001615(k)).
- # https://oeis.org/A291487
- # Known terms:
- # 1, 1, 0, 4, 12, 75, 300, 1950, 13650, 122850, 1160250, 13340250, 140390250, 1825073250, 25318743450, 370489869750, 5503458610650, 93558796381050, 1643961707838450, 30815473745606550, 596477734382780250, 12526032422038385250, 272871020017346000250, 6276033460398958005750
- for k in (1..30) {
- print(k!.inverse_psi_min || 0, ", ")
- }
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