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.

A087463 Generalized multiplicative Jacobsthal sequence.

Original entry on oeis.org

0, 1, 1, 0, 5, 11, 0, 43, 85, 0, 341, 683, 0, 2731, 5461, 0, 21845, 43691, 0, 174763, 349525, 0, 1398101, 2796203, 0, 11184811, 22369621, 0, 89478485, 178956971, 0, 715827883, 1431655765, 0, 5726623061, 11453246123, 0, 45812984491, 91625968981, 0
Offset: 0

Views

Author

Paul Barry, Sep 08 2003

Keywords

Comments

Set A001045(3n)=0 in A001045.
2^n = A087462(n) + a(n) + A087464(n) provides a decomposition of Pascal's triangle.

Programs

  • PARI
    concat(0, Vec(-x*(4*x^4-2*x^3+x+1)/((x+1)*(2*x-1)*(x^2-x+1)*(4*x^2+2*x+1)) + O(x^100))) \\ Colin Barker, Nov 02 2015

Formula

a(n) = Sum_{k=0..n} if (mod(n*k, 3)=1, 1, 0)*C(n, k).
a(n) = (2/9)*(1-cos(2*Pi*n/3))*(2^n-(-1)^n).
From Colin Barker, Nov 02 2015: (Start)
a(n) = 7*a(n-3)+8*a(n-6) for n>5.
G.f.: -x*(4*x^4-2*x^3+x+1) / ((x+1)*(2*x-1)*(x^2-x+1)*(4*x^2+2*x+1)).
(End)

A087464 Generalized multiplicative Jacobsthal sequence.

Original entry on oeis.org

0, 0, 2, 0, 6, 10, 0, 42, 86, 0, 342, 682, 0, 2730, 5462, 0, 21846, 43690, 0, 174762, 349526, 0, 1398102, 2796202, 0, 11184810, 22369622, 0, 89478486, 178956970, 0, 715827882, 1431655766, 0, 5726623062, 11453246122, 0, 45812984490, 91625968982, 0
Offset: 0

Views

Author

Paul Barry, Sep 08 2003

Keywords

Comments

2^n = A087462(n) + A087463(n) + a(n) provides a decomposition of Pascal's triangle.

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0,0,7,0,0,8},{0,0,2,0,6,10},40] (* Harvey P. Dale, Aug 31 2015 *)
  • PARI
    concat(vector(2), Vec(2*x^2*(2*x^3-3*x^2-1)/((x+1)*(2*x-1)*(x^2-x+1)*(4*x^2+2*x+1)) + O(x^100))) \\ Colin Barker, Nov 02 2015

Formula

a(n) = Sum_{k=0..n} if(mod(n*k, 3)=2, 1, 0) * C(n, k).
a(n) = (2/9)*(2^n-3*0^n+2*(-1)^n)*(1-cos(2*Pi*n/3)).
From Colin Barker, Nov 02 2015: (Start)
a(n) = 7*a(n-3)+8*a(n-6) for n>5.
G.f.: 2*x^2*(2*x^3-3*x^2-1) / ((x+1)*(2*x-1)*(x^2-x+1)*(4*x^2+2*x+1)).
(End)
Showing 1-2 of 2 results.