a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 2. Also a(n) = 3^n*C(n-1), where C = A000108 (Catalan numbers).
A025226
a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 2. Also a(n) = 3^n*C(n-1), where C = A000108 (Catalan numbers).
Terms
- a(0) =3a(1) =9a(2) =54a(3) =405a(4) =3402a(5) =30618a(6) =288684a(7) =2814669a(8) =28146690a(9) =287096238a(10) =2975361012a(11) =31241290626a(12) =331638315876
External references
- oeis: A025226