A336699 a(n) = A000265(1+A000265(sigma(A000265(n)))), where A000265(k) gives the odd part of k, and sigma is the sum of divisors function.

1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 5, 7, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 5, 1, 7, 5, 3, 1, 1, 11, 1, 3, 1, 5, 1, 1, 1, 29, 1, 5, 1, 7, 3, 5, 1, 3, 1, 1, 1, 1, 1, 7, 1, 11, 1, 9, 5, 1, 1, 5, 7, 19, 5, 1, 3, 1, 1, 3, 1, 61, 11, 11, 1, 7, 3, 1, 1, 23, 5, 1, 1, 1, 1, 1, 1, 25, 29, 5, 1, 13, 5, 7, 1, 1

Offset: 1

Author

Antti Karttunen, Aug 02 2020

Keywords

• nonn
• look

Comments

See the "lacunae" in the scatter plot. - Antti Karttunen, Mar 27 2022

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384
• Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
• Jon Maiga, Computer-generated formulas for A336699, Sequence Machine.
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A000265, A000593, A002131, A082903, A161942, A171435, A322250, A336698, A336700, A336701, A336844 [= a(A003961(n))], A351565.

Programs

PARI

A000265(n) = (n>>valuation(n,2));
A336699(n) = A000265(1+A000265(sigma(A000265(n))));

Formula

a(n) = A000265(1+A000265(A000593(n))) = A000265(1+A161942(A000265(n))).

a(n) = A336698(A000265(n)).

From Antti Karttunen, Mar 27 2022: (Start)

a(n) = A351565(A000593(n)).

[The following formulas were discovered by Sequence Machine]:

a(n) = A351565(A002131(n)) = A000265(1+A000265(A002131(n))).

a(n) = A336698(1+A322250(n)).

a(n) = A171435(A000593(n)+A082903(n)).

(End)