A185678 Riordan array (((1+x)/(1-x-x^2))^m, x*A000108(x)), m=3.
1, 6, 1, 21, 7, 1, 59, 29, 8, 1, 147, 97, 38, 9, 1, 339, 292, 145, 48, 10, 1, 741, 835, 496, 204, 59, 11, 1, 1557, 2347, 1606, 771, 275, 71, 12, 1, 3174, 6640, 5083, 2736, 1130, 359, 84, 13, 1, 6317, 19220, 16046, 9406, 4323, 1587, 457, 98, 14, 1, 12330, 57469, 51152, 31932, 15886, 6480, 2157, 570, 113, 15, 1
Offset: 0
Examples
1; 6,1; 21,7,1; 59,29,8,1; 147,97,38,9,1; 339,292,145,48,10,1; 741,835,496,204,59,11,1; 1557,2347,1606,771,275,71,12,1;
Links
- Vladimir Kruchinin and D. V. Kruchinin, Composita and their properties, arXiv:1103.2582 [math.CO], 2011-2013.
Formula
R(n,k,m) = k*sum(i=0..n-k, sum(j=m..i+m, binomial(j-1,m-1) * binomial(j,i+m-j)) * binomial(2*(n-i)-k-1,n-i-1)/(n-i)), k>0, m=3, R(n,0,m)=sum(i=m..n+m, binomial(i-1,m-1) * binomial(i,n+m-i)).