A324830 - OEIS

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A324830

Number of divisors d of n such that A323243(d) is a multiple of 3.

6

1, 1, 2, 1, 1, 3, 2, 1, 3, 1, 1, 4, 2, 3, 3, 2, 1, 4, 2, 1, 4, 2, 1, 5, 1, 3, 4, 4, 2, 4, 1, 2, 3, 1, 3, 5, 2, 3, 4, 1, 1, 6, 2, 2, 5, 1, 1, 7, 3, 1, 3, 4, 2, 6, 1, 5, 4, 3, 1, 5, 2, 2, 6, 2, 3, 6, 1, 1, 3, 5, 2, 7, 1, 3, 4, 4, 3, 6, 2, 2, 5, 1, 1, 8, 2, 3, 4, 3, 2, 7, 4, 1, 3, 2, 3, 8, 1, 5, 5, 2, 2, 5, 1, 5, 7

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OFFSET

1,3

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000 (based on Hans Havermann's factorization of A156552)

Index entries for sequences related to binary expansion of n

Index entries for sequences computed from indices in prime factorization

Index entries for sequences related to sigma(n)

FORMULA

a(n) = A000005(n) - (A324831(n) + A324832(n)).

For all n >= 1, a(A000040(n)) = 2-A000035(n).

PROG

(PARI) A324830(n) = sumdiv(n, d, (0==(A323243(d))%3));

CROSSREFS

Cf. A000005, A156552, A323243, A324831, A324832.

Sequence in context: A345033 A329359 A235682 * A141110 A325758 A280073

Adjacent sequences: A324827 A324828 A324829 * A324831 A324832 A324833

KEYWORD

nonn

AUTHOR

Antti Karttunen, Mar 16 2019

STATUS

approved