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A001842 Expansion of Sum_{n>=0} x^(4*n+3)/(1 - x^(4*n+3)). 12
0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 2, 0, 0, 1, 1, 0, 2, 1, 1, 1, 0, 0, 2, 1, 0, 2, 1, 0, 2, 0, 2, 1, 0, 1, 2, 0, 0, 2, 1, 1, 2, 1, 1, 1, 1, 0, 2, 0, 0, 2, 2, 1, 2, 0, 1, 2, 0, 1, 3, 0, 0, 2, 1, 0, 2, 2, 1, 1, 0, 0, 3, 1, 2, 2, 1, 0, 2, 0, 1, 2, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,16

COMMENTS

Number of divisors of n of form 4*k+3: a(n) = A001227(n)-A001826(n). - Reinhard Zumkeller, Apr 18 2006

LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000

Michael Gilleland, Some Self-Similar Integer Sequences

FORMULA

a(A072437(n)) = 0. - Benoit Cloitre, Apr 24 2003

G.f.: Sum_{k>=1} x^(3*k)/(1 - x^(4*k)). - Ilya Gutkovskiy, Sep 11 2019

a(n) = Sum_{d|n} (binomial(d,3) mod 2). - Ridouane Oudra, Nov 19 2019

MAPLE

with(numtheory): seq(add(binomial(d, 3) mod 2, d in divisors(n)), n=0..100); # Ridouane Oudra, Nov 19 2019

MATHEMATICA

Join[{0}, Table[d = Divisors[n]; Length[Select[d, Mod[#, 4] == 3 &]], {n, 100}]] (* T. D. Noe, Aug 10 2012 *)

CROSSREFS

Cf. A001227, A001826, A072437.

Sequence in context: A325334 A280287 A147696 * A216654 A326016 A326033

Adjacent sequences:  A001839 A001840 A001841 * A001843 A001844 A001845

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified April 13 01:36 EDT 2021. Contains 342934 sequences. (Running on oeis4.)