a(n) = binomial(2^n + 3*n - 1, n).A132687a(n) = binomial(2^n + 3*n - 1, n).Terms a(0) =1a(1) =4a(2) =36a(3) =560a(4) =17550a(5) =1370754a(6) =324540216a(7) =267212177232External referencesoeis: A132687