OFFSET
0,2
PROG
(PARI) a(n)=local(A, B, C, m); A=matrix(1, 1); A[1, 1]=1; for(m=2, n+3, B=A^2; C=matrix(m, m); for(j=1, m, for(k=1, j, if(j<3 || k==j || k>m-1, C[j, k]=1, if(k==1, C[j, k]=B[j-1, 1], C[j, k]=B[j-1, k-1])); )); A=C); A[n+3, 3]
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Sep 13 2004
STATUS
approved