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.

A038223 Bottom line of 3-wave sequence A038196, also bisection of A006356.

Original entry on oeis.org

1, 6, 31, 157, 793, 4004, 20216, 102069, 515338, 2601899, 13136773, 66326481, 334876920, 1690765888, 8536537209, 43100270734, 217609704247, 1098693409021, 5547212203625, 28007415880892, 141407127676248
Offset: 0

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Suggested by the Steinbach heptagon polynomial p^3 - p^2*(1 - p) - 2*p(1 - p)^2 + (1 - p)^3 = (1 - 5 p + 6 p^2 - p^3). - Roger L. Bagula, Sep 20 2006

Programs

  • Mathematica
    p[x_] := 1 - 5 x + 6 x^2 - x^3; q[x_] := ExpandAll[x^3*p[1/x]]; Table[ SeriesCoefficient[ Series[x/q[x], {x, 0, 30}], n], {n, 0, 30}] (* Roger L. Bagula, Sep 20 2006 *)
  • PARI
    k=3; M(k)=matrix(k,k,i,j,min(i,j)); v(k)=vector(k,i,1); a(n)=vecmax(v(k)*M(k)^n)

Formula

Let v(3)=(1, 1, 1), let M(3) be the 3 X 3 matrix m(i, j) =min(i, j), so M(3)=(1, 1, 1)/(1, 2, 2)/(1, 2, 3); then a(n)= Max ( v(3)*M(3)^n) - Benoit Cloitre, Oct 03 2002
G.f.: 1/(1-6x+5x^2-x^3). - Roger L. Bagula and Gary W. Adamson, Sep 20 2006

Extensions

More terms from Benoit Cloitre, Oct 03 2002
Edited by R. J. Mathar, Aug 02 2008