Expansion of g/(1 - x^2*g^5), where g = 1+x*g^2 is the g.f. of A000108.

Terms

a(0) =1a(1) =1a(2) =3a(3) =11a(4) =42a(5) =163a(6) =639a(7) =2523a(8) =10015a(9) =39918a(10) =159622a(11) =639951a(12) =2571129a(13) =10348227a(14) =41710908a(15) =168336109a(16) =680096275a(17) =2750205427a(18) =11130353849a(19) =45077337022a(20) =182673844561a(21) =740682995826