A275826 Least k such that n! divides d(k!) (d = A000005, k > 0).

1, 2, 6, 8, 20, 20, 28, 36, 36, 56, 90, 90, 120, 126, 126, 126, 172, 172, 342, 342, 374, 380, 464, 464, 464, 464, 464, 464, 464, 464, 847, 847, 1056, 1105, 1105, 1105, 1105, 1105, 1330, 1330, 1728, 1728, 1728, 1728, 1728, 2410, 2856, 2856, 2856, 2856

Offset

1,2

Comments

From Michael De Vlieger, Aug 10 2016: (Start)

Values in a(n): 1, 2, 6, 8, 20, 28, 36, 56, 90, 120, 126, 172, 342, 374, 380, 464, 847, 1056, 1105, 1330, 1728, 2410, 2856, ...

First position of values in a(n): 1, 2, 3, 4, 5, 7, 8, 10, 11, 13, 14, 17, 19, 21, 22, 23, 31, 33, 34, 39, 41, 46, 47, ...

(End)

Links

Chai Wah Wu, Table of n, a(n) for n = 1..500

Example

a(4) = 8 because A000005(8!) = 96 is divisible by 4! = 24.

Mathematica

Table[k = 1; While[! Divisible[DivisorSigma[0, k!], n!], k++]; k, {n, 50}] (* Michael De Vlieger, Aug 10 2016 *)

Prog

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

Crossrefs

Cf. A000005, A027423, A275476.

Sequence in context: A002618 A135616 A069553 * A371238 A143481 A093968

Adjacent sequences: A275823 A275824 A275825 * A275827 A275828 A275829

Keyword

nonn

Author

Altug Alkan, Aug 10 2016

Status

approved