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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A308671 a(n) = Sum_{d|n} d^(d^2). 3
 1, 17, 19684, 4294967313, 298023223876953126, 10314424798490535546171968756, 256923577521058878088611477224235621321608, 6277101735386680763835789423207666416102355444468329480209 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..8. FORMULA L.g.f.: -log(Product_{k>=1} (1 - x^k)^(k^(k^2-1))) = Sum_{k>=1} a(k)*x^k/k. MATHEMATICA a[n_] := DivisorSum[n, #^(#^2) &]; Array[a, 8] (* Amiram Eldar, May 11 2021 *) PROG (PARI) {a(n) = sumdiv(n, d, d^d^2)} (PARI) N=20; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-x^k)^(k^(k^2-1)))))) CROSSREFS Column k=2 of A308674. Cf. A000005, A062796, A308670. Sequence in context: A308962 A191964 A230638 * A308670 A308571 A283719 Adjacent sequences: A308668 A308669 A308670 * A308672 A308673 A308674 KEYWORD nonn AUTHOR Seiichi Manyama, Jun 16 2019 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 April 15 14:37 EDT 2024. Contains 371689 sequences. (Running on oeis4.)