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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A377398 Expansion of e.g.f. (2 - exp(x))^3.

Original entry on oeis.org

1, -3, 3, 9, 3, -63, -357, -1431, -5037, -16623, -52917, -164871, -506877, -1545183, -4684677, -14152311, -42653517, -128353743, -385847637, -1159115751, -3480492957, -10447770303, -31355893797, -94092847191, -282328873197, -847087282863, -2541463175157
Offset: 0

Views

Author

Seiichi Manyama, Oct 27 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, 3, (-1)^k*k!*binomial(3, k)*stirling(n, k, 2));
    
  • PARI
    a(n) = sum(k=0, 3, (-1)^k*2^(3-k)*binomial(3, k)*k^n);

Formula

a(n) = 5*a(n-1) - 6*a(n-2) - 24 for n > 2.
a(n) = Sum_{k=0..3} (-1)^k * k! * binomial(3,k) * Stirling2(n,k).
a(n) = Sum_{k=0..3} (-1)^k * 2^(3-k) * binomial(3,k) * k^n.
G.f.: (1-4*x) * (1-5*x+12*x^2)/((1-x) * (1-2*x) * (1-3*x)).
a(n) = 3*2^(n+1) - 3^n - 12 for n > 0. - Stefano Spezia, Oct 27 2024
a(0) = 1; a(n) = Sum_{k=1..n} (1 - 4 * k/n) * binomial(n,k) * a(n-k). - Seiichi Manyama, Oct 27 2024

A377583 Expansion of e.g.f. (1 + x * exp(x))^4.

Original entry on oeis.org

1, 4, 20, 108, 616, 3620, 21624, 129892, 778208, 4621572, 27080680, 156080804, 883304976, 4905620356, 26743018904, 143219056740, 754280089024, 3911369843204, 19995029207496, 100885122939172, 502952669726960, 2480084192804484, 12107351426245240, 58565261434872548
Offset: 0

Views

Author

Seiichi Manyama, Nov 02 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*sum(k=0, n, k^(n-k)*binomial(4, k)/(n-k)!);

Formula

a(n) = n! * Sum_{k=0..n} k^(n-k) * binomial(4,k)/(n-k)!.
G.f.: (1 - 36*x + 595*x^2 - 5970*x^3 + 40543*x^4 - 196752*x^5 + 702365*x^6 - 1871250*x^7 + 3740456*x^8 - 5614440*x^9 + 6362360*x^10 - 5588880*x^11 + 3979680*x^12 - 2196672*x^13 + 663552*x^14) / ((1-x)^2*(1-2*x)^3*(1-3*x)^4*(1-4*x)^5).
Showing 1-2 of 2 results.