Coefficient of x^n in the expansion of ( (1-x+x^2) / (1-x) )^(3*n).

A372412

Coefficient of x^n in the expansion of ( (1-x+x^2) / (1-x) )^(3*n).

Terms

    a(0) =1a(1) =0a(2) =6a(3) =9a(4) =78a(5) =225a(6) =1293a(7) =4851a(8) =24174a(9) =101583a(10) =480531a(11) =2123913a(12) =9869973a(13) =44669742a(14) =206614827a(15) =946394109a(16) =4378019310a(17) =20189406771a(18) =93556141449a(19) =433284753414

External references