0,2

Equals column 0 of triangle V =A136230,where column k of V = column 0 of P^(3k+2) such that column k of P^2 = column 0 of V^(k+1), for k>=0 and where P =A136220.

(PARI) /* Generate using matrix product recurrences of triangle P=A136220:*/ {a(n)=local(P=Mat(1), U, PShR); if(n>0, 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<#R, P[r, c], (U^c)[r-c+1, 1]))))); (P^2)[n+1, 1]}

Cf.A136225(P^2),A136220(P),A136230(V);A136217.

Sequence in context:A088181A058864A332237*A046165A227264A373865

Adjacent sequences:A136223A136224A136225*A136227A136228A136229

Paul D. Hanna,Jan 28 2008

approved