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.

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A113647 Triangle of numbers related to the generalized Catalan sequence C(2;n+1)=A064062(n+1), n>=0.

Original entry on oeis.org

1, 1, 3, 1, 7, 13, 1, 15, 41, 67, 1, 31, 113, 247, 381, 1, 63, 289, 783, 1545, 2307, 1, 127, 705, 2271, 5361, 9975, 14589, 1, 255, 1665, 6207, 16929, 36879, 66057, 95235, 1, 511, 3841, 16255, 50113, 123871, 255985, 446455, 636925, 1, 1023, 8705, 41215, 141441
Offset: 0

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Author

Wolfdieter Lang, Jan 13 2006

Keywords

Comments

This triangle, called Y(2,1), appears in the totally asymmetric exclusion process for the (unphysical) values alpha=2, beta=1. See the Derrida et al. refs. given under A064094, where the triangle entries are called Y_{N,K} for given alpha and beta.
The main diagonal (M=1) gives the generalized Catalan sequence C(2,n):=A064062(n).
The diagonal sequences give A064062(n+1), A115137, A115150-A115153, for n+1>= M=1,..,6.

Examples

			Triangle begins:
  1;
  1,3;
  1,7,13;
  1,15,41,67;
  1,31,113,247,381;
  ...
113=a(4,3)= a(4,2) + 2*a(3,3)= 31 + 2*41.
		

Crossrefs

Row sums give A115136.

Formula

a(n, n+1)=A064062(n+1) (main diagonal with M=1); a(n, n-M+2)= a(n, n-M+1) + 2*a(n-1, n-M+2), M>=2; a(n, 1)=1; n>=0.
G.f. for diagonal sequence M=1: GY(1, x):=(2*c(2*x)-1)/(1+x) with c(x) g.f. of A000108 (Catalan); for M=2: GY(2, x)=(1-2*x)*GY(1, x)-1; for M>=3: GY(M, x)= GY(M-1, x) -2*x*GY(M-2, x) + x^(M-2).
G.f. for diagonal sequence M (solution to the above given recurrence): GY(M, x)= (x^(M-1)/(1+x))*( 2^(M+1)*x*(p(M, 2*x)-(2*x)*p(M+1, 2*x)*c(2*x))+1), with c(x) g.f. of A000108 (Catalan) and p(n, x):= -((1/sqrt(x))^(n+1))*S(n-1, 1/sqrt(x)) with Chebyshev's S(n, x) polynomials given in A049310.

A115138 A sequence related to Catalan numbers A000108.

Original entry on oeis.org

1, -1, 1, 15, 113, 783, 5361, 36879, 255985, 1794063, 12689393, 90505231, 650379249, 4705157135, 34244198385, 250572963855, 1842382110705, 13605619630095, 100872203796465, 750556607938575, 5602962592235505, 41952165966643215, 314983352736153585
Offset: 0

Views

Author

Wolfdieter Lang, Jan 13 2006

Keywords

Comments

See also A115150, the third diagonal of triangle A113647 (called Y(2,1)).

Examples

			15= a(3) = A062992(3) - 4*A062992(2) = 67 - 4*13.
		

Formula

(1-4*x)*(2*c(2*x)-1)/(1+x) with c(x) g.f. of A000108 (Catalan).
a(n)= A113647(n, n-1), n>=2.
a(n)= b(n)-4*b(n-1) with b(n):=A062992(n), n>=2; a(0)=1, a(1)=-1.
Showing 1-2 of 2 results.