a(n) = (7^n/n!^2) * Product_{k=0..n-1} (14k+2)*(14k+5).

A185401

a(n) = (7^n/n!^2) * Product_{k=0..n-1} (14k+2)*(14k+5).

Terms

    a(0) =1a(1) =70a(2) =37240a(3) =28674800a(4) =25943525300

External references