A129102 Column 2 of triangle A129100; also equals column 0 of matrix power A129100^4.

1, 4, 20, 136, 1360, 21204, 537748, 22891448, 1675538928, 214841466180, 48966357498452, 20069542925092392, 14932742187505262032, 20328765555338724571508, 50972424276515393704138196

Offset

0,2

Links

Table of n, a(n) for n=0..14.

Prog

(PARI) a(n)=local(A=Mat(1), B); for(m=1, n+3, B=matrix(m, m); for(r=1, m, for(c=1, r, if(r==c || r==1 || r==2, B[r, c]=1, if(c==1, B[r, 1]=sum(i=1, r-1, A[r-1, i]), B[r, c]=(A^(2^(c-1)))[r-c+1, 1])); )); A=B); return(A[n+3, 3])

Crossrefs

Cf. A129100 (triangle); A129092 (column 0), A129101 (column 1), A129103 (column 3).

Sequence in context: A270665 A330538 A141716 * A129099 A244756 A292932

Adjacent sequences: A129099 A129100 A129101 * A129103 A129104 A129105

Keyword

nonn

Author

Paul D. Hanna, Mar 29 2007

Status

approved