Number of simple skew-merged permutations with n elements.

Terms

a(0) =2a(1) =2a(2) =8a(3) =16a(4) =44a(5) =108a(6) =284a(7) =740a(8) =1966a(9) =5254a(10) =14172a(11) =38476a(12) =105122a(13) =288754a(14) =797036a(15) =2209588a(16) =6149618a(17) =17176186a(18) =48129284a(19) =135261796a(20) =381169532a(21) =1076824852a(22) =3049109912a(23) =8652239496a(24) =24600592454a(25) =70075316198a(26) =199955694616