A069789 Smallest k>n such that sigma(n) divides sigma(k).

2, 5, 6, 12, 6, 11, 14, 24, 18, 17, 14, 28, 20, 15, 23, 25, 22, 45, 24, 26, 31, 30, 30, 38, 48, 41, 54, 39, 38, 46, 42, 68, 35, 53, 42, 117, 74, 54, 60, 58, 44, 62, 86, 60, 90, 51, 62, 75, 74, 80, 55, 97, 85, 56, 66, 87, 79, 88, 87, 78, 75, 69, 103, 192, 78, 70, 134, 82, 77

Offset: 1

Author

Benoit Cloitre, May 01 2002

Keywords

• easy
• nonn

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000203.

Programs

Mathematica

a[n_] := Module[{k = n+1, s = DivisorSigma[1, n]}, While[!Divisible[DivisorSigma[1, k], s], k++]; k]; Array[a, 100] (* Amiram Eldar, Jun 03 2022 *)

PARI

for(s=1,80,n=s+1; while(frac(sigma(n)/sigma(s))>0,n++); print1(n,","); )