A336691 Number of distinct prime factors of 1+sigma(n).

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 3, 1, 2, 2, 2, 1, 1, 2, 1, 2, 2, 2, 1, 2, 1, 1, 1, 2, 2, 1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 2, 2, 2, 1, 2, 1, 2, 3, 1, 1

Offset

1,9

Links

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

Index entries for sequences related to sigma(n)

Formula

a(n) = A001221(1+A000203(n)) = A001221(A088580(n)).

Prog

(PARI) A336691(n) = omega(1+sigma(n));

Crossrefs

Cf. A000203, A001221, A088580, A058062, A332459, A336692, A336693, A336694, A336695.

Sequence in context: A353742 A238747 A101873 * A177991 A146289 A214575

Adjacent sequences: A336688 A336689 A336690 * A336692 A336693 A336694

Keyword

nonn

Author

Antti Karttunen, Jul 31 2020

Status

approved