login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A001877 Number of divisors of n of form 5k+2. 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 x^(5n+2)/(1-x^(5n+2)), n=0..inf.

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 *)

CROSSREFS

Sequence in context: A219490 A277142 A240592 * A112712 A026608 A264049

Adjacent sequences:  A001874 A001875 A001876 * A001878 A001879 A001880

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 15 15:14 EDT 2019. Contains 328030 sequences. (Running on oeis4.)