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

Author

Paul D. Hanna, Dec 25 2007

Keywords

• nonn

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.

Crossrefs

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

Programs

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])}