Ceiling of Gamma(n+2/7)/Gamma(2/7).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =12a(6) =63a(7) =393a(8) =2863a(9) =23715a(10) =220205a(11) =2264966a(12) =25561752a(13) =314044379a(14) =4172303890a(15) =59604341273a(16) =911094930877