A113647 - OEIS

A113647

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

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

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

0,3

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.

LINKS

Table of n, a(n) for n=0..49.

B. Derrida, E. Domany and D. Mukamel, An exact solution of a one-dimensional asymmetric exclusion model with open boundaries, J. Stat. Phys. 69, 1992, 667-687; eqs. (20), (21), p. 672.

Wolfdieter Lang, First 10 rows.

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.

EXAMPLE

Triangle begins:

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.

Sequence in context: A263446 A297192 A218592 * A370381 A161380 A257852

Adjacent sequences: A113644 A113645 A113646 * A113648 A113649 A113650

KEYWORD

nonn,easy,tabl

AUTHOR

Wolfdieter Lang, Jan 13 2006

STATUS

approved