a(n) = Sum_{k=0..n} binomial(n,2k)*A002426(k).

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =26a(6) =68a(7) =176a(8) =454a(9) =1174a(10) =3052a(11) =7976a(12) =20932a(13) =55108a(14) =145448a(15) =384704a(16) =1019462a(17) =2706214a(18) =7194956a(19) =19155896a(20) =51065260a(21) =136284236a(22) =364097912a(23) =973654240a(24) =2605983772a(25) =6980545276a(26) =18712478072a(27) =50196568144a(28) =134739960904a(29) =361892443592