**a(0)=1, for n>=1 a(n)=sum(k=0,n,8^k*N(n,k)) where N(n,k) =1/n*C(n,k)*C(n,k+1) are the Narayana numbers (A001263).**

*1, 1, 9, 89, 945, 10577, 123129, 1476841, 18130401, 226739489, 2878666857*

*1 seqfan posts*

Index of A-numbers in seqfan: by ascending order by month by frequency by keyword

Links to OEIS content are included according to The OEIS End-User License Agreement .