Coefficient of x^n in the expansion of ( (1+x) / (1-x^3)^3 )^n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =10a(4) =49a(5) =151a(6) =532a(7) =2353a(8) =9745a(9) =37675a(10) =150851a(11) =624603a(12) =2561476a(13) =10426625a(14) =42800031a(15) =176797510a(16) =730069649a(17) =3016004001a(18) =12492387775a(19) =51845882845a(20) =215363387699a(21) =895504027855