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 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A159555 Numbers m where m^2 divides A159553(m), where A159553(m) = Sum_{k=0..m} binomial(m,k) * gcd(m,k). 0
 1, 6, 22, 72, 114, 148, 164, 260, 261, 780, 1078, 1184, 1266, 2952, 4674, 21868 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For the purpose of this sequence, gcd(m,0) = m. No other term up to 15000. - Michel Marcus, Sep 06 2019 LINKS MAPLE A159068 := proc(n) option remember; add(binomial(n, k)*gcd(k, n), k=1..n) ; end: A159553 := proc(n) option remember ; A159068(n)+n; end: isA159555 := proc(n) if A159553(n) mod ( n^2) = 0 then true; else false; fi; end: for n from 1 do if isA159555(n) then printf("%d, \n", n) ; fi; od: # R. J. Mathar, Apr 29 2009 PROG (PARI) f(n) = sum(k=0, n, binomial(n, k) * gcd(n, k)); \\ A159553 isok(n) = !(f(n) % n^2); \\ Michel Marcus, Sep 05 2019 CROSSREFS Cf. A159458, A159553, A159554. Sequence in context: A171495 A178706 A276779 * A032195 A217530 A111566 Adjacent sequences: A159552 A159553 A159554 * A159556 A159557 A159558 KEYWORD nonn,more AUTHOR Leroy Quet, Apr 15 2009 EXTENSIONS Extended by R. J. Mathar, Apr 29 2009 a(14)-a(15) from Ray Chandler, Jun 18 2009 a(16) from Jinyuan Wang, Jul 25 2022 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 3 03:21 EST 2022. Contains 358510 sequences. (Running on oeis4.)