Second differences of A001515 (or A144301).

A144647

Second differences of A001515 (or A144301).

Terms

    a(0) =1a(1) =4a(2) =25a(3) =199a(4) =1936a(5) =22411a(6) =301939a(7) =4649800a(8) =80654599a(9) =1556992441a(10) =33120019516a(11) =769887934729

External references