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

Terms

a(0) =1a(1) =1a(2) =1a(3) =7a(4) =33a(5) =101a(6) =319a(7) =1226a(8) =4705a(9) =17017a(10) =61901a(11) =231837a(12) =872031a(13) =3260856a(14) =12220846a(15) =46062632a(16) =174030177a(17) =657910813a(18) =2490889801a(19) =9448650829a(20) =35890996733a(21) =136473161741a(22) =519476028237