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.

A328054 Expansion of e.g.f. log(1 + x / (1 - x)^2).

Original entry on oeis.org

0, 1, 3, 8, 18, 24, 0, 720, 15120, 161280, 1088640, 3628800, 0, 479001600, 18681062400, 348713164800, 3923023104000, 20922789888000, 0, 6402373705728000, 364935301226496000, 9731608032706560000, 153272826515128320000, 1124000727777607680000, 0, 620448401733239439360000
Offset: 0

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Author

Ilya Gutkovskiy, Oct 03 2019

Keywords

Comments

Logarithmic transform of A001563.

Crossrefs

Cf. A001563, A008588 (positions of 0's), A009306, A082579, A328055.

Programs

  • Maple
    b:= proc(n) option remember; n*n! end:
    a:= proc(n) option remember; `if`(n=0, 0, b(n)-
          add(binomial(n, j)*j*b(n-j)*a(j), j=1..n-1)/n)
        end:
    seq(a(n), n=0..25);  # Alois P. Heinz, Oct 04 2019
  • Mathematica
    nmax = 25; CoefficientList[Series[Log[1 + x/(1 - x)^2], {x, 0, nmax}], x] Range[0, nmax]!
    Join[{0}, Table[2 (n - 1)! (1 - Cos[Pi n/3]), {n, 1, 25}]]
  • PARI
    my(x='x+O('x^30)); concat(0, Vec(serlaplace(log(1 + x / (1 - x)^2)))) \\ Michel Marcus, Oct 04 2019

Formula

E.g.f.: log(1 + Sum_{k>=1} k * x^k).
D-finite with recurrence a(n+3) = n*(n+1)*(n+2)*a(n) - 2*(n+2)*(n+1)*a(n+1) + 2*(n+2)*a(n+2). - Robert Israel, Jan 16 2023