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A293451 Number of proper divisors of form 4k+1. 4
0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 1, 2, 2, 2, 1, 1, 2, 1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 1, 2, 1, 1, 3, 1, 1, 1, 1, 3, 2, 2, 1, 2, 2, 1, 1, 2, 1, 2, 1, 1, 3, 1, 3, 2, 1, 2, 1, 2, 1, 2, 1, 2, 3, 1, 1, 2, 1, 2, 2, 2, 1, 2, 3, 1, 2, 1, 1, 4, 2, 1, 1, 1, 2, 1, 1, 2, 3, 3, 1, 2, 1, 2, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,10

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

FORMULA

a(n) = Sum_{d|n, d<n} [1 == d mod 4].

a(n) = A091954(n) - A293513(n).

a(n) = A001826(n) - A121262(n-1).

G.f.: Sum_{k>=1} x^(8*k-6) / (1 - x^(4*k-3)). - Ilya Gutkovskiy, Apr 14 2021

PROG

(PARI) A293451(n) = sumdiv(n, d, (d<n)*(1==(d%4)));

CROSSREFS

Cf. A001826, A091954, A121262, A293513, A293901.

Sequence in context: A093997 A157196 A300410 * A063014 A286361 A097295

Adjacent sequences:  A293448 A293449 A293450 * A293452 A293453 A293454

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 19 2017

STATUS

approved

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Last modified September 22 19:36 EDT 2021. Contains 347608 sequences. (Running on oeis4.)