Binomial coefficient C(7n,n-2).

A004370

Binomial coefficient C(7n,n-2).

Terms

    a(0) =1a(1) =21a(2) =378a(3) =6545a(4) =111930a(5) =1906884a(6) =32468436a(7) =553270671a(8) =9440350920a(9) =161322559475

External references