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A001877 Number of divisors of n of form 5k+2; a(0) = 0. 5
0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 2, 0, 2, 0, 1, 1, 1, 0, 1, 1, 2, 0, 2, 0, 1, 1, 2, 0, 1, 0, 2, 0, 2, 1, 2, 1, 1, 0, 1, 0, 3, 0, 2, 0, 1, 1, 2, 1, 1, 1, 2, 0, 2, 0, 2, 1, 1, 0, 2, 0, 2, 1, 2, 0, 2, 1, 2, 0, 2, 0, 3, 0, 2, 0, 1, 2, 1, 0, 1, 1, 2, 0, 4, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,13

LINKS

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

FORMULA

G.f.: Sum_{n>=0} x^(5n+2)/(1-x^(5n+2)).

G.f.: Sum_(n>=1} x^(2*n)/(1-x^(5*n))). - Joerg Arndt, Jan 30 2011

MATHEMATICA

Join[{0}, Table[d = Divisors[n]; Length[Select[d, Mod[#, 5] == 2 &]], {n, 100}]] (* T. D. Noe, Aug 10 2012 *)

Table[Count[Divisors[n], _?(Mod[#, 5]==2&)], {n, 0, 90}] (* Harvey P. Dale, May 20 2017 *)

PROG

(PARI) a(n) = if (n==0, 0, sumdiv(n, d, (d % 5)==2)); \\ Michel Marcus, Feb 28 2021

CROSSREFS

Cf. A001876, A001878, A001899.

Sequence in context: A341021 A277142 A240592 * A339896 A112712 A026608

Adjacent sequences:  A001874 A001875 A001876 * A001878 A001879 A001880

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified June 12 08:13 EDT 2021. Contains 344943 sequences. (Running on oeis4.)