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.

A121833 Expansion of 1/(1-x^2-x^3-x^6).

Original entry on oeis.org

1, 0, 1, 1, 1, 2, 3, 3, 6, 7, 10, 15, 20, 28, 41, 55, 79, 111, 154, 218, 306, 427, 603, 844, 1184, 1665, 2334, 3276, 4602, 6454, 9062, 12721, 17850, 25059, 35173, 49363, 69294, 97257, 136507, 191610, 268937, 377480, 529841, 743674, 1043828, 1465125
Offset: 0

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Author

Jon E. Schoenfield, Aug 27 2006

Keywords

Comments

Number of compositions of n into parts 2, 3, and 6. [Joerg Arndt, Sep 03 2013]

Programs

  • Magma
    I:=[1,0,1,1,1,2]; [n le 6 select I[n] else Self(n-2)+Self(n-3)+Self(n-6): n in [1..50]]; // Vincenzo Librandi, Sep 03 2013
  • Mathematica
    CoefficientList[Series[1 / (1 - x^2 - x^3 - x^6), {x, 0, 50}], x] (* Vincenzo Librandi, Sep 03 2013 *)
    LinearRecurrence[{0,1,1,0,0,1},{1,0,1,1,1,2},50] (* Harvey P. Dale, Dec 16 2016 *)

Formula

a(n) = a(n-2) + a(n-3) + a(n-6).
G.f.: -1 / ( (1+x)*(x^5-x^4+x^3+x-1) ). - R. J. Mathar, Aug 09 2017