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.

A131387 Product of the nonzero digital products of n for all the bases 1 to n (a 'total digital-product factorial').

Original entry on oeis.org

1, 1, 1, 1, 2, 4, 12, 48, 48, 192, 2880, 2880, 25920, 552960, 3265920, 1935360, 116121600, 278691840, 9405849600, 26754416640, 94058496000, 3210529996800, 869100503040000, 423789959577600, 927040536576000, 135612787064832000
Offset: 1

Views

Author

Hieronymus Fischer, Jul 08 2007

Keywords

Programs

  • PARI
    a(n) = {p = 1; for (b=2, n, digs = digits(n, b); p *= prod(k=1, #digs, if (digs[k], digs[k], 1));); return (p);} \\ Michel Marcus, Jul 15 2013

Formula

a(n)=product{1<=p<=n, dp_p(n)} where dp_p(n) = product of the nonzero digits of n in base p.