cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A387151 a(n) = n*n! / Product_{k=1..n} radical(k), where radical(n) is the product of distinct prime factors of n, cf. A007947.

Original entry on oeis.org

0, 1, 2, 3, 8, 10, 12, 14, 64, 216, 240, 264, 576, 624, 672, 720, 6144, 6528, 20736, 21888, 46080, 48384, 50688, 52992, 221184, 1152000, 1198080, 11197440, 23224320, 24053760, 24883200, 25712640, 424673280, 437944320, 451215360, 464486400, 2866544640
Offset: 0

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Author

David A. Corneth and Peter Luschny, Aug 18 2025

Keywords

Crossrefs

Cf. A387140.

Programs

  • Maple
    A387151 := n -> n*n! / mul(NumberTheory:-Radical(k), k = 1..n): seq(A387151(n), n = 0..36);
  • Mathematica
    k = 1; {0}~Join~Reap[Do[k *= Times @@ FactorInteger[n][[;; , 1]]; Sow[n*n!/k], {n, 36}] ][[-1, 1]] (* Michael De Vlieger, Aug 18 2025 *)

Formula

a(n) = n! / A387140(n) for n >= 1.