Binomial coefficient C(13,n).

Terms

a(0) =1a(1) =13a(2) =78a(3) =286a(4) =715a(5) =1287a(6) =1716a(7) =1716a(8) =1287a(9) =715a(10) =286a(11) =78a(12) =13a(13) =1