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.

A087211 a(n) = floor((1+2^n+3^n)/3).

Original entry on oeis.org

1, 2, 4, 12, 32, 92, 264, 772, 2272, 6732, 20024, 59732, 178512, 534172, 1599784, 4793892, 14370752, 43090412, 129227544, 387595252, 1162610992, 3487483452, 10461751304, 31383855812, 94148771232, 282440721292, 847310979064
Offset: 0

Views

Author

Paul Barry, Aug 26 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Floor[(1+2^n+3^n)/3],{n,0,30}] (* or *) LinearRecurrence[{4,-1,-6},{1,2,4,12},30] (* Harvey P. Dale, May 21 2018 *)

Formula

G.f.: (1-2*x-3*x^2+4*x^3)/((1+x)*(1-2*x)*(1-3*x));
E.g.f.: (exp(3*x)+exp(2*x)+2*exp(0)-exp(-x))/3;
a(n) = (3^n+2^n+2*0^n-(-1)^n)/3.
a(n) = 2*A094039(n), n>0. - R. J. Mathar, Feb 13 2015
a(n) = 4*a(n-1) - a(n-2) - 6*a(n-3). - Wesley Ivan Hurt, Apr 25 2023

A094038 Binomial transform of (Pell(-n)+Pell(n))/2.

Original entry on oeis.org

0, 1, 2, 8, 24, 84, 280, 960, 3264, 11152, 38048, 129920, 443520, 1514304, 5170048, 17651712, 60266496, 205762816, 702517760, 2398545920, 8189147136, 27959497728, 95459694592, 325919784960, 1112759746560, 3799199420416
Offset: 0

Views

Author

Paul Barry, Apr 23 2004

Keywords

Comments

Also binomial transform of Pell(n)(1-(-1)^n)/2.
a(n+2) = A088013(n+1) + A007070(n) - Creighton Dement, Oct 23 2004

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{4,0,-8,4},{0,1,2,8},30] (* Harvey P. Dale, Jan 01 2016 *)

Formula

G.f.: x(1-2x)/((1-2x^2)(1-4x+2x^2));
a(n)=(sqrt(2)/8)((2+sqrt(2))^n-(2-sqrt(2))^n+(sqrt(2))^n-(-sqrt(2))^n).
Showing 1-2 of 2 results.