210980549208domain: NAppears in sequencesBinomial coefficient C(3n,n-12).at n=10A004330Binomial coefficient C(6n,n-1).at n=10A004356Binomial coefficients C(n,56).at n=10A017720Binomial coefficients C(66,n).at n=10A017782Column 1 of triangle A107867; a(n) = binomial( n*(n+1)/2 + n+1, n).at n=10A107869