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.

A344398 a(n) = (-1)^n * F_{n}((-1)^n * n), where F_{n}(x) is the Fubini polynomial.

Original entry on oeis.org

1, 1, 10, 111, 8676, 243005, 49729758, 2634606331, 1026912225160, 88276603008249, 55954905981282210, 7103694104486331671, 6655958151527584785900, 1171100778886715057133493, 1521436331153097968932487206, 354408430829377435361459172915, 609729139653483641913607434550800
Offset: 0

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Author

Peter Luschny, May 21 2021

Keywords

Crossrefs

The coefficients of the Fubini polynomials are A131689.
Cf. A094420.

Programs

  • Maple
    F := proc(n) option remember; if n = 0 then return 1 fi;
    expand(add(binomial(n, k)*F(n-k)*x, k = 1..n)) end:
    a := n -> (-1)^n*subs(x = (-1)^n*n, F(n)):
    seq(a(n), n = 0..17);
  • Mathematica
    F[n_][x_] := If[n == 0, 1, Sum[k! StirlingS2[n, k] x^k, {k, 0, n}]];
    a[n_] := (-1)^n F[n][(-1)^n*n];
    Table[a[n], {n, 0, 16}] (* Jean-François Alcover, May 09 2024 *)
  • SageMath
    @cached_function
    def F(n):
        R. = PolynomialRing(ZZ)
        if n == 0: return R(1)
        return R(sum(binomial(n, k)*F(n - k)*x for k in (1..n)))
    def a(n):
        return (-1)^n*F(n).substitute(x = (-1)^n*n)
    print([a(n) for n in range(17)])