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

Terms

a(0) =1a(1) =2a(2) =6a(3) =23a(4) =94a(5) =392a(6) =1659a(7) =7107a(8) =30734a(9) =133880a(10) =586576a(11) =2582142a(12) =11411371a(13) =50597900a(14) =224986467a(15) =1002867878a(16) =4479814606a(17) =20049099908a(18) =89878609344a(19) =403521966942