The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A284281 a(n) = Sum_{d|n, d == 3 (mod 5)} d. 12
 0, 0, 3, 0, 0, 3, 0, 8, 3, 0, 0, 3, 13, 0, 3, 8, 0, 21, 0, 0, 3, 0, 23, 11, 0, 13, 3, 28, 0, 3, 0, 8, 36, 0, 0, 21, 0, 38, 16, 8, 0, 3, 43, 0, 3, 23, 0, 59, 0, 0, 3, 13, 53, 21, 0, 36, 3, 58, 0, 3, 0, 0, 66, 8, 13, 36, 0, 68, 26, 0, 0, 29, 73, 0, 3, 38, 0, 94, 0, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Seiichi Manyama, Table of n, a(n) for n = 1..10000 FORMULA G.f.: Sum_{k>=0} (5*k + 3)*x^(5*k+3)/(1 - x^(5*k+3)). - Ilya Gutkovskiy, Mar 25 2017 Sum_{k=1..n} a(k) = c * n^2 + O(n*log(n)), where c = Pi^2/60 = 0.164493... (A013661 / 10). - Amiram Eldar, Nov 26 2023 MATHEMATICA Table[Sum[If[Mod[d, 5] == 3, d, 0], {d, Divisors[n]}], {n, 80}] (* Indranil Ghosh, Mar 24 2017 *) PROG (PARI) for(n=1, 82, print1(sumdiv(n, d, if(Mod(d, 5)==3, d, 0)), ", ")) \\ Indranil Ghosh, Mar 24 2017 (Python) from sympy import divisors def a(n): return sum([d for d in divisors(n) if d%5==3]) # Indranil Ghosh, Mar 24 2017 CROSSREFS Cf. A013661, A109699, A284152. Cf. Sum_{d|n, d=k mod 5} d: A284097 (k=1), A284280 (k=2), this sequence (k=3), A284103 (k=4). Sequence in context: A272974 A063691 A359967 * A075874 A181634 A230652 Adjacent sequences: A284278 A284279 A284280 * A284282 A284283 A284284 KEYWORD nonn,easy AUTHOR Seiichi Manyama, Mar 24 2017 STATUS approved

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

Last modified December 11 14:52 EST 2023. Contains 367727 sequences. (Running on oeis4.)