Coefficient of x^n in the expansion of ((1+x) * (1+x^4))^n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =5a(5) =26a(6) =91a(7) =246a(8) =589a(9) =1459a(10) =4126a(11) =12706a(12) =38831a(13) =113400a(14) =320412a(15) =903176a(16) =2594541a(17) =7594921a(18) =22366459a(19) =65579983a(20) =191126530a(21) =556001580a(22) =1621739890a(23) =4749240860a(24) =13943353711a(25) =40956336901a(26) =120247940476a(27) =352999059076