A336924 a(n) = spf(1+sigma(n)), where spf is the smallest prime factor and sigma is the sum of divisors function.

2, 2, 5, 2, 7, 13, 3, 2, 2, 19, 13, 29, 3, 5, 5, 2, 19, 2, 3, 43, 3, 37, 5, 61, 2, 43, 41, 3, 31, 73, 3, 2, 7, 5, 7, 2, 3, 61, 3, 7, 43, 97, 3, 5, 79, 73, 7, 5, 2, 2, 73, 3, 5, 11, 73, 11, 3, 7, 61, 13, 3, 97, 3, 2, 5, 5, 3, 127, 97, 5, 73, 2, 3, 5, 5, 3, 97, 13, 3, 11, 2, 127, 5, 3, 109, 7, 11, 181, 7, 5, 113, 13

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences related to sigma(n)

Formula

a(n) = A020639(1+A000203(n)) = A020639(A088580(n)).

Prog

(PARI) A336924(n) = (factor((1+sigma(n)))[1, 1]);

Crossrefs

Cf. A000203, A020639, A071189, A088580.

Cf. also A336691, A336692, A336693, A336694, A336695, A336696.

Sequence in context: A100030 A029603 A204202 * A025124 A030996 A368580

Adjacent sequences: A336921 A336922 A336923 * A336925 A336926 A336927

Keyword

nonn

Author

Antti Karttunen, Aug 09 2020

Status

approved