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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A115154 Triangle of numbers related to the generalized Catalan sequence C(3;n+1) = A064063(n+1), n>=0.

Original entry on oeis.org

1, 1, 4, 1, 13, 25, 1, 40, 115, 190, 1, 121, 466, 1036, 1606, 1, 364, 1762, 4870, 9688, 14506, 1, 1093, 6379, 20989, 50053, 93571, 137089, 1, 3280, 22417, 85384, 235543, 516256, 927523, 1338790, 1, 9841, 77092, 333244, 1039873, 2588641, 5371210
Offset: 0

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Author

Wolfdieter Lang, Feb 23 2006

Keywords

Comments

This triangle, called Y(3,1), appears in the totally asymmetric exclusion process for the (unphysical) values alpha=3, 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(3,n+1):=A064063(n+1).
The diagonal sequences give A064063(n+1), A115188-A115192 for n+1>= M=1,..,6.

Examples

			Triangle begins:
  1;
  1,   4;
  1,  13,  25;
  1,  40, 115,  190;
  1, 121, 466, 1036, 1606;
  ...
466 = a(4,3) = a(4,2) + 3*a(3,3) = 121 + 3*115.
		

Crossrefs

Row sums give A115187.

Formula

a(n,n+1)=A064063(n+1) (main diagonal with M=1); a(n,n-M+2)= a(n,n-M+1) + 3*a(n-1,n-M+2), M>=2; a(n,1)=1; n>=0.
G.f. for diagonal sequence M=1: GY(1,x):=(3*c(3*x)-1)/(2+x) with c(x) the o.g.f. of A000108 (Catalan); for M=2: GY(2,x)=(1-3*x)*GY(1,x)-1; for M>=3: GY(M,x)= GY(M-1,x) - 3*x*GY(M-2,x) + 2*x^(M-2).
G.f. for diagonal sequence M (solution to the above given recurrence): GY(M,x)= (x^(M-1)/(1+x))*( 3^(M+1)*x*(p(M,3*x)-(3*x)*p(M+1,3*x)*c(3*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.
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