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

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =13a(5) =26a(6) =62a(7) =132a(8) =274a(9) =614a(10) =1315a(11) =2955a(12) =6423a(13) =14058a(14) =30838a(15) =67170a(16) =147553a(17) =322304a(18) =706400a(19) =1546128a(20) =3382752a(21) =7408261a(22) =16208271a(23) =35489093a(24) =77672999a(25) =170021833a(26) =372181083a(27) =814611385a(28) =1783211187a(29) =3903138418