Number of permutations of 1..n with displacements restricted to {-7,-6,-5,-4,-3,0,1,2}.

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =13a(5) =35a(6) =89a(7) =221a(8) =499a(9) =1146a(10) =2755a(11) =6750a(12) =16570a(13) =40293a(14) =97355a(15) =234629a(16) =565632a(17) =1365768a(18) =3303221a(19) =7992751a(20) =19333657a(21) =46743931a(22) =112983171a(23) =273083004a(24) =660115058a(25) =1595837810a(26) =3858133501a(27) =9327445000a(28) =22549449187a(29) =54512990509