cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A290750 Inverse Euler transform of [3, 13, 55, 233, 987, 4181, 17711, 75025, 317811, ...], Fibonacci(3*k+1).

Original entry on oeis.org

3, 7, 24, 76, 272, 948, 3496, 12920, 48792, 185912, 716472, 2781600, 10878640, 42789292, 169181280, 671865840, 2678679360, 10716650484, 43007271768, 173072547360, 698235684336, 2823329204964, 11439823954664, 46440709197120, 188856966713360, 769241291697640, 3137871076653336, 12817512478814400
Offset: 1

Views

Author

N. J. A. Sloane, Aug 12 2017

Keywords

Crossrefs

Cf. A033887.

Programs

  • Maple
    read(transforms): with(combinat); F:=fibonacci;
    s1:=[seq(F(3*n+1),n=1..40)];
    EULERi(s1);
  • Mathematica
    mob[m_, n_] := If[Mod[m, n] == 0, MoebiusMu[m/n], 0];
    EULERi[b_] := Module[{a, c, i, d}, c = {}; For[i = 1, i <= Length[b], i++, c = Append[c, i b[[i]] - Sum[c[[d]] b[[i - d]], {d, 1, i - 1}]]]; a = {}; For[i = 1, i <= Length[b], i++, a = Append[a, (1/i)*Sum[mob[i, d] c[[d]], {d, 1, i}]]]; Return[a]];
    EULERi[Table[Fibonacci[3k + 1], {k, 1, 30}]] (* Jean-François Alcover, Aug 06 2018 *)

Formula

a(n) ~ (2 + sqrt(5))^n / n. - Vaclav Kotesovec, Oct 09 2019