a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-2)*a(2) for n >= 3.

A025239

a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-2)*a(2) for n >= 3.

Terms

    a(0) =2a(1) =3a(2) =6a(3) =21a(4) =78a(5) =318a(6) =1356a(7) =5997a(8) =27222a(9) =126138a(10) =594132a(11) =2836290a(12) =13692300a(13) =66729180a(14) =327855768a(15) =1622216829a(16) =8076311142a(17) =40427919714a(18) =203353800324

External references