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.

Showing 1-2 of 2 results.

A108742 Row sums of a triangle related to the Jacobsthal polynomials.

Original entry on oeis.org

1, 2, 3, 7, 12, 24, 45, 86, 164, 312, 595, 1133, 2159, 4113, 7836, 14929, 28442, 54187, 103235, 196680, 374708, 713881, 1360062, 2591144, 4936560, 9404967, 17918025, 34136815, 65036305, 123904968, 236059553, 449732674, 856815475, 1632375855
Offset: 0

Views

Author

Paul Barry, Jun 22 2005

Keywords

Comments

Row sums of A108756.

Programs

  • Mathematica
    LinearRecurrence[{1,2,0,-1},{1,2,3,7},40] (* Harvey P. Dale, Feb 21 2016 *)

Formula

G.f.: (1 + x - x^2)/(1 - x - 2*x^2 + x^4).
a(n) = a(n - 1) + 2*a(n - 2) - a(n - 4) for n >= 4.
a(n) = Sum_{0 <= k <= n} binomial(floor((n + k + 1)/2) + k, floor((n + k)/2) - k).

A109220 Expansion of (1+x-x^2)/(1-2x-2x^2+x^4).

Original entry on oeis.org

1, 3, 7, 20, 53, 143, 385, 1036, 2789, 7507, 20207, 54392, 146409, 394095, 1060801, 2855400, 7685993, 20688691, 55688567, 149899116, 403489373, 1086088287, 2923466753, 7869210964, 21181866061, 57016065763, 153472396895
Offset: 0

Views

Author

Paul Barry, Jun 22 2005

Keywords

Comments

Transform of 2^n under matrix A108756.

Formula

a(n)=2a(n-1)+2a(n-2)-a(n-4); a(n)=a(n)=sum{k=0..n, binomial(floor((n+k+1)/2)+k, floor((n+k)/2)-k)*2^k}.
Showing 1-2 of 2 results.