Number of permutations of 1..n with displacements restricted to {-6,-5,-4,-3,-1,0,2}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =23a(6) =51a(7) =111a(8) =225a(9) =469a(10) =997a(11) =2125a(12) =4569a(13) =9742a(14) =20728a(15) =44075a(16) =93629a(17) =199251a(18) =424146a(19) =902940a(20) =1922351a(21) =4091125a(22) =8706560a(23) =18528914a(24) =39433024a(25) =83926690a(26) =178622780a(27) =380165386a(28) =809106324a(29) =1722001443