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.

A257813 G.f. satisfies: A(x,y) = 1-x + y*x + Series_Reversion( x/A(x,y)^2 ).

Original entry on oeis.org

1, 0, 1, 0, 2, 0, 0, 4, 5, 0, 0, 8, 38, 14, 0, 0, 16, 184, 262, 42, 0, 0, 32, 720, 2460, 1602, 132, 0, 0, 64, 2480, 16360, 25837, 9260, 429, 0, 0, 128, 7840, 87920, 268134, 237870, 52040, 1430, 0, 0, 256, 23296, 408128, 2109040, 3638386, 2023992, 288494, 4862, 0, 0, 512, 66048, 1701504, 13676128, 40049492, 43815744, 16394336, 1590638, 16796, 0
Offset: 0

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Author

Paul D. Hanna, May 10 2015

Keywords

Comments

The rightmost nonzero numbers in this triangle form the Catalan numbers (A000108).

Examples

			This triangle begins:
1;
0, 1;
0, 2, 0;
0, 4, 5, 0;
0, 8, 38, 14, 0;
0, 16, 184, 262, 42, 0;
0, 32, 720, 2460, 1602, 132, 0;
0, 64, 2480, 16360, 25837, 9260, 429, 0;
0, 128, 7840, 87920, 268134, 237870, 52040, 1430, 0;
0, 256, 23296, 408128, 2109040, 3638386, 2023992, 288494, 4862, 0;
0, 512, 66048, 1701504, 13676128, 40049492, 43815744, 16394336, 1590638, 16796, 0;
0, 1024, 180480, 6531840, 76845728, 349863976, 653001202, 487491424, 128720399, 8765044, 58786, 0;
0, 2048, 478720, 23485440, 386423488, 2571281744, 7476451420, 9591548748, 5139351752, 991185638, 48412190, 208012, 0; ...
Row sums (A120970) begin:
[1, 1, 2, 9, 60, 504, 4946, 54430, 655362, 8496454, 117311198, ...],
the g.f. of which satisfies: G(x) = 1 + Series_Reversion(x/G(x)^2).
GENERATING FUNCTION.
G.f.: A(x,y) = 1 + x*y + x^2*(2*y) + x^3*(4*y + 5*y^2) +
x^4*(8*y + 38*y^2 + 14*y^3) +
x^5*(16*y + 184*y^2 + 262*y^3 + 42*y^4) +
x^6*(32*y + 720*y^2 + 2460*y^3 + 1602*y^4 + 132*y^5) +
x^7*(64*y + 2480*y^2 + 16360*y^3 + 25837*y^4 + 9260*y^5 + 429*y^6) +
x^8*(128*y + 7840*y^2 + 87920*y^3 + 268134*y^4 + 237870*y^5 + 52040*y^6 + 1430*y^7) +
x^9*(256*y + 23296*y^2 + 408128*y^3 + 2109040*y^4 + 3638386*y^5 + 2023992*y^6 + 288494*y^7 + 4862*y^8) +...
where
A(x,y) = 1-x + y*x + Series_Reversion( x/A(x,y)^2 ).
RELATED SERIES.
A(x/A(x,y)^2, y) = 1 + y*x + (-2*y^2 + 2*y)*x^2 +
(3*y^3 - 7*y^2 + 4*y)*x^3 +
(-4*y^4 + 6*y^3 - 10*y^2 + 8*y)*x^4 +
(5*y^5 - 27*y^4 - 18*y^3 + 24*y^2 + 16*y)*x^5 +
(-6*y^6 - 14*y^5 - 312*y^4 + 60*y^3 + 240*y^2 + 32*y)*x^6 +
(7*y^7 - 147*y^6 - 1745*y^5 - 1675*y^4 + 2360*y^3 + 1136*y^2 + 64*y)*x^7 +
(-8*y^8 - 348*y^7 - 10744*y^6 - 25146*y^5 + 10246*y^4 + 21616*y^3 + 4256*y^2 + 128*y)*x^8 +
(9*y^9 - 1361*y^8 - 60738*y^7 - 267656*y^6 - 84094*y^5 + 265552*y^4 + 133952*y^3 + 14080*y^2 + 256*y)*x^9 +...
		

Crossrefs

Programs

  • PARI
    {T(n,k) = local(A=[1]);for(i=1,n, A=Vec(1 + (y-1)*x + serreverse(x/Ser(A)^2))); polcoeff(A[n+1],k,y)}
    for(n=0,10,for(k=0,n, print1(T(n,k),", "));print(""))

Formula

G.f. A(x,y) satisfies: A(x/A(x,y)^2, y) = 1+x + (y-1)*x/A(x,y)^2.