A136222 Column 1 of triangle A136220; also equals column 0 of U^2 = A136233 where U = A136228.

1, 2, 10, 75, 753, 9534, 146353, 2647628, 55251994, 1308089217, 34669446816, 1017575959652, 32778617719852, 1150083357364646, 43669478546754372, 1784505372378097160, 78098473768259907870, 3645038134074497689782

Offset

0,2

Comments

P = A136220 is a triangular matrix where column k of P^3 equals column 0 of P^(3k+3) such that column 0 of P^3 equals column 0 of P shift one place left.

Links

Table of n, a(n) for n=0..17.

Prog

(PARI) {a(n)=local(P=Mat(1), U, PShR); if(n==0, 1, for(i=0, n, PShR=matrix(#P, #P, r, c, if(r>=c, if(r==c, 1, if(c==1, 0, P[r-1, c-1])))); U=P*PShR^2; U=matrix(#P+1, #P+1, r, c, if(r>=c, if(r<#P+1, U[r, c], if(c==1, (P^3)[ #P, 1], (P^(3*c-1))[r-c+1, 1])))); P=matrix(#U, #U, r, c, if(r>=c, if(r<#U, P[r, c], (U^c)[r-c+1, 1])))); P[n+2, 2])}

Crossrefs

Cf. A136220 (P), A136228 (U), A136233 (U^2); other columns of P: A136221, A136223, A136224.

Sequence in context: A358437 A289679 A352270 * A184356 A292631 A295098

Adjacent sequences: A136219 A136220 A136221 * A136223 A136224 A136225

Keyword

nonn

Author

Paul D. Hanna, Dec 25 2007

Status

approved