OFFSET
0,2
PROG
(PARI) {a(n)=local(M=matrix(n+1, n+1, r, c, if(r>=c, 1))); for(i=1, n, M=matrix(n+1, n+1, r, c, if(r>=c, if(c==1, if(r==1, 1, sum(j=1, r-1, (M*M~)[r-j, j])), (M*M~)[r-c+1, c])))); sum(k=0, n, M[n+1, k+1]^2)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Sep 05 2011
STATUS
approved