Column 1 of triangle A107870; a(n) = C(n*(n+1)/2 + n+2, n).

A107872

Column 1 of triangle A107870; a(n) = C(n*(n+1)/2 + n+2, n).

Terms

    a(0) =1a(1) =4a(2) =21a(3) =165a(4) =1820a(5) =26334a(6) =475020a(7) =10295472a(8) =260932815a(9) =7575968400a(10) =247994680648

External references