Number of permutations of 1..n with displacements restricted to {-4,-3,-1,0,2}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =20a(6) =37a(7) =72a(8) =140a(9) =277a(10) =553a(11) =1085a(12) =2129a(13) =4185a(14) =8228a(15) =16208a(16) =31902a(17) =62747a(18) =123449a(19) =242860a(20) =477830a(21) =940205a(22) =1849830a(23) =3639492a(24) =7160647a(25) =14088415a(26) =27719015a(27) =54537120a(28) =107301253a(29) =211114467