Column 0 of triangle A107873; a(n) = C( n*(n-1)/2 + n+3, n).

A107874

Column 0 of triangle A107873; a(n) = C( n*(n-1)/2 + n+3, n).

Terms

    a(0) =1a(1) =4a(2) =15a(3) =84a(4) =715a(5) =8568a(6) =134596a(7) =2629575a(8) =61523748a(9) =1677106640a(10) =52179482355

External references