a(n) = floor( Gamma(n+5/7)/Gamma(5/7) ).

Terms

a(0) =1a(1) =0a(2) =1a(3) =3a(4) =12a(5) =58a(6) =332a(7) =2232a(8) =17225a(9) =150103a(10) =1458149a(11) =15623031a(12) =183012659a(13) =2326875239a(14) =31911431853a(15) =469553925838