A082053 Sum of divisors of n that are not of the form 4k+3.

1, 3, 1, 7, 6, 9, 1, 15, 10, 18, 1, 25, 14, 17, 6, 31, 18, 36, 1, 42, 22, 25, 1, 57, 31, 42, 10, 49, 30, 54, 1, 63, 34, 54, 6, 88, 38, 41, 14, 90, 42, 86, 1, 73, 60, 49, 1, 121, 50, 93, 18, 98, 54, 90, 6, 113, 58, 90, 1, 150, 62, 65, 31, 127, 84, 130, 1, 126, 70, 102, 1, 192

Offset

1,2

Comments

a(A002145(n))=1.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Formula

G.f.: Sum_{k>=1} x^k*(1 + 2*x^k + 4*x^(3*k) + 3*x^(4*k) + 2*x^(5*k))/(1 - x^(4*k))^2. - Ilya Gutkovskiy, Sep 12 2019

Mathematica

sd[n_]:= Total[Select[Divisors[n], !IntegerQ[(# - 3) / 4]&]]; Array[sd, 100] (* Vincenzo Librandi, May 17 2013 *)

Prog

(PARI) for(n=1, 100, print1(sumdiv(n, d, if(d%4!=3, d))", "))

Crossrefs

Cf. A000203, A050449, A050452, A050460, A078181, A078182, A082052.

Sequence in context: A118228 A359079 A245684 * A322753 A136035 A132307

Adjacent sequences: A082050 A082051 A082052 * A082054 A082055 A082056

Keyword

nonn,easy

Author

Ralf Stephan, Apr 02 2003

Status

approved