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.

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A295182 a(n) = n! * [x^n] exp(-n*x)/(1 - x)^n.

Original entry on oeis.org

1, 0, 2, 6, 72, 620, 8640, 122346, 2156672, 41367672, 905126400, 21646532270, 570077595648, 16268377195044, 502096929431552, 16629319748711250, 588938142209310720, 22196966267762213744, 887352465220427317248, 37496112562144553167062, 1670071417348195942400000, 78195398849926292810318940
Offset: 0

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Author

Ilya Gutkovskiy, Nov 16 2017

Keywords

Comments

The n-th term of the n-fold exponential convolution of A000166 with themselves.

Crossrefs

Programs

  • Maple
    S:= series((exp(-x)/(1-x))^n,x,30):
    seq(n!*coeff(S,x,n),n=0..29); # Robert Israel, Nov 16 2017
  • Mathematica
    Table[n! SeriesCoefficient[Exp[-n x]/(1 - x)^n, {x, 0, n}], {n, 0, 21}]

Formula

a(n) = A295181(n,n).
a(n) ~ phi^(3*n - 1/2) * n^n / (5^(1/4) * exp(n*(1 + 1/phi))), where phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Nov 16 2017
a(n) = n! * Sum_{k=0..n} (-n)^(n-k) * binomial(n+k-1,k)/(n-k)!. - Seiichi Manyama, Apr 25 2025

A295188 Decimal expansion of phi^3 * exp(1 - 1/phi), where phi is the golden ratio.

Original entry on oeis.org

6, 2, 0, 6, 5, 2, 7, 0, 3, 8, 3, 9, 7, 1, 6, 3, 7, 3, 1, 0, 0, 0, 7, 4, 0, 5, 3, 2, 1, 8, 6, 5, 8, 0, 5, 8, 5, 2, 7, 8, 0, 5, 2, 8, 7, 0, 8, 4, 7, 9, 6, 2, 0, 2, 2, 9, 2, 6, 0, 7, 5, 3, 9, 6, 8, 7, 9, 0, 5, 8, 4, 9, 3, 7, 5, 6, 1, 4, 1, 8, 4, 4, 4, 3, 5, 6, 3, 1, 1, 2, 2, 6, 1, 0, 2, 3, 0, 5, 0, 6, 3, 7, 0, 2, 4
Offset: 1

Views

Author

Vaclav Kotesovec, Nov 16 2017

Keywords

Examples

			6.206527038397163731000740532186580585278052870847962022926...
		

Crossrefs

Programs

  • Maple
    evalf(((1+sqrt(5))/2)^3 * exp(1 - 2/(1+sqrt(5))), 120);
  • Mathematica
    RealDigits[GoldenRatio^3 * Exp[1 - 1/GoldenRatio], 10, 110][[1]]
  • PARI
    phi=(sqrt(5)+1)/2; phi^3*exp(2-phi) \\ Charles R Greathouse IV, Nov 21 2024

Formula

Equals ((1+sqrt(5))/2)^3 * exp(1 - 2/(1+sqrt(5))).
Equals limit n->infinity (A066399(n)/n!)^(1/n).
Equals limit n->infinity (A239761(n)/n!)^(1/n).
Equals limit n->infinity (A295183(n)/n!)^(1/n).
Showing 1-2 of 2 results.