A275476 Least k such that n divides d(k!) where d = A000005 (k > 0).

1, 2, 6, 3, 6, 6, 15, 4, 10, 6, 12, 7, 28, 15, 6, 5, 18, 10, 20, 7, 15, 12, 24, 8, 21, 28, 10, 15, 60, 6, 63, 8, 12, 18, 28, 11, 76, 20, 28, 9, 81, 15, 46, 12, 10, 24, 48, 8, 27, 21, 18, 28, 110, 10, 24, 15, 20, 60, 120, 7, 243, 63, 15, 15, 28, 12, 68, 18, 24, 28

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

a(3) = 6 because A000005(6!) = 30 is divisible by 3.

Mathematica

Table[k = 1; While[! Divisible[DivisorSigma[0, k!], n], k++]; k, {n, 120}] (* Michael De Vlieger, Aug 07 2016 *)
With[{c=Table[{k, DivisorSigma[0, k!]}, {k, 250}]}, Table[SelectFirst[ c, Divisible[ #[[2]], n]&], {n, 70}]][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 17 2019 *)

Prog

(PARI) a(n) = {my(k = 1); while(numdiv(k!) % n != 0, k++); k; }

Crossrefs

Cf. A000005, A027423.

Sequence in context: A177209 A274439 A280342 * A185380 A136695 A337115

Adjacent sequences: A275473 A275474 A275475 * A275477 A275478 A275479

Keyword

nonn

Author

Altug Alkan, Jul 29 2016

Status

approved