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.

A006102 Gaussian binomial coefficient [ n,4 ] for q=3.

Original entry on oeis.org

1, 121, 11011, 925771, 75913222, 6174066262, 500777836042, 40581331447162, 3287582741506063, 266307564861468823, 21571273555248777493, 1747282899667791058573, 141530177899268957392924, 11463951511551877750726204, 928580264181940191843785764, 75215006575885931519565302404
Offset: 4

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Keywords

References

  • J. Goldman and G.-C. Rota, The number of subspaces of a vector space, pp. 75-83 of W. T. Tutte, editor, Recent Progress in Combinatorics. Academic Press, NY, 1969.
  • I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p. 99.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.

Crossrefs

Partial sums of A226804. - Christian Krause, Dec 26 2022

Programs

  • Magma
    r:=4; q:=3; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 02 2016
  • Maple
    A006102:=-1/((z-1)*(81*z-1)*(3*z-1)*(9*z-1)*(27*z-1)); # conjectured (correctly) by Simon Plouffe in his 1992 dissertation
  • Mathematica
    Table[QBinomial[n, 4, 3], {n, 4, 24}] (* Vincenzo Librandi, Aug 02 2016 *)
  • Sage
    [gaussian_binomial(n,4,3) for n in range(4,20)] # Zerinvary Lajos, May 25 2009
    

A227524 Expansion of 1/((1-3x)(1-9x)(1-27x)).

Original entry on oeis.org

1, 39, 1170, 32670, 891891, 24169509, 653373540, 17648258940, 476567558181, 12867905191779, 347438670325110, 9380891170278810, 253284485241566871, 6838684914320250849, 184644527001833063880, 4985402537886183692280, 134605871302457221445961
Offset: 0

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Author

Vincenzo Librandi, Jul 17 2013

Keywords

Crossrefs

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-3*x)*(1-9*x)*(1-27*x))));
    
  • Magma
    I:=[1, 39, 1170]; [n le 3 select I[n] else 39*Self(n-1)-351*Self(n-2)+729*Self(n-3): n in [1..25]];
  • Mathematica
    CoefficientList[Series[1 / ((1 - 3 x) (1 - 9 x) (1 - 27 x)), {x, 0, 30}], x]
    LinearRecurrence[{39,-351,729},{1,39,1170},20] (* Harvey P. Dale, Jul 04 2022 *)

Formula

G.f.: 1/((1-3*x)*(1-9*x)*(1-27*x)).
a(n) = 3^n*(3^(n+1)-1)*(3^(n+2)-1)/16.
a(0)=1, a(1)=39, a(2)=1170; for n>2, a(n) = 39*a(n-1)-351*a(n-2)+729*a(n-3).
a(n)-27*a(n-1) = A016142(n), with a(-1)=0; a(n) = A226804(n)-81*A226804(n-1), with A226804(-1)=0. [Bruno Berselli, Jul 17 2013]
Showing 1-2 of 2 results.