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

1,1

Links

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

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 *)

Prog

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

Crossrefs

Cf. A000203.

Sequence in context: A275522 A110975 A190120 * A332683 A086334 A346759

Adjacent sequences: A069786 A069787 A069788 * A069790 A069791 A069792

Keyword

easy,nonn

Author

Benoit Cloitre, May 01 2002

Status

approved