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A111965 Riordan array (1/sqrt(1-6x+5x^2),x/(1-6x+5x^2)). 1
1, 3, 1, 11, 6, 1, 45, 31, 9, 1, 195, 156, 60, 12, 1, 873, 781, 360, 98, 15, 1, 3989, 3906, 2055, 684, 145, 18, 1, 18483, 19531, 11403, 4395, 1155, 201, 21, 1, 86515, 97656, 62132, 26856, 8260, 1800, 266, 24, 1, 408105, 488281, 334260, 158692, 55188, 14190 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Row sums are A111966. Factors as (1/(1-x),x/(1-x))*(1/sqrt(1-4x),x/sqrt(1-4x)).

LINKS

Table of n, a(n) for n=0..50.

FORMULA

Number triangle T(n, k)=sum{j=0..n, C((k+2j-1)/2, j)C(j, n-j-k)(-6)^(k-n+2j)5^(n-k-j)}

EXAMPLE

1;

3,1;

11,6,1;

45,31,9,1;

195,156,60,12,1;

873,781,360,98,15,1;

CROSSREFS

Sequence in context: A092808 A113955 A110165 * A110440 A135574 A008969

Adjacent sequences:  A111962 A111963 A111964 * A111966 A111967 A111968

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Aug 23 2005

STATUS

approved

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Last modified October 23 14:36 EDT 2019. Contains 328345 sequences. (Running on oeis4.)