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.

A002625 Expansion of 1/((1-x)^3*(1-x^2)^2*(1-x^3)).

Original entry on oeis.org

1, 3, 8, 17, 33, 58, 97, 153, 233, 342, 489, 681, 930, 1245, 1641, 2130, 2730, 3456, 4330, 5370, 6602, 8048, 9738, 11698, 13963, 16563, 19538, 22923, 26763, 31098, 35979, 41451, 47571, 54390, 61971, 70371, 79660, 89901, 101171, 113540, 127092, 141904, 158068, 175668, 194804, 215568
Offset: 0

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Comments

Number of (integer) partitions of n into 3 sorts of 1's, 2 sorts of 2's, and 1 sort of 3's. - Joerg Arndt, May 17 2013

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Partial sums of A097701.

Programs

  • Maple
    A002625:=1/(z**2+z+1)/(z+1)**2/(z-1)**6; [Simon Plouffe in his 1992 dissertation.]
  • Mathematica
    CoefficientList[Series[1/((1-x)^3*(1-x^2)^2*(1-x^3)),{x,0,50}],x] (* Vincenzo Librandi, Feb 25 2012 *)
    LinearRecurrence[{3,-1,-4,2,2,2,-4,-1,3,-1},{1,3,8,17,33,58,97,153,233,342},50] (* Harvey P. Dale, Sep 24 2022 *)
  • PARI
    Vec(1/(1-x)^3/(1-x^2)^2/(1-x^3)+O(x^99)) \\ Charles R Greathouse IV, Apr 30 2012

Formula

a(n) = floor((n+1)*(135*(-1)^n + 6*n^4 + 144*n^3 + 1256*n^2 + 4744*n + 6785)/8640+1/2). - Tani Akinari, Oct 07 2012