a(n) = Product_{k=0..n-1} (n+4*k+1).

A384258

a(n) = Product_{k=0..n-1} (n+4*k+1).

Terms

    a(0) =1a(1) =2a(2) =21a(3) =384a(4) =9945a(5) =332640a(6) =13627845a(7) =660602880a(8) =36974963025

External references