Number of length n arrays of permutations of 0..n-1 with each element moved by -2 to 2 places and equal numbers of elements moved upwards and downwards.

A263738

Number of length n arrays of permutations of 0..n-1 with each element moved by -2 to 2 places and equal numbers of elements moved upwards and downwards.

Terms

    a(0) =1a(1) =2a(2) =4a(3) =10a(4) =19a(5) =43a(6) =90a(7) =202a(8) =434a(9) =971a(10) =2133a(11) =4780a(12) =10634a(13) =23918a(14) =53667a(15) =121159a(16) =273464a(17) =619510a(18) =1404284a(19) =3190779a(20) =7256305a(21) =16529258a(22) =37686110a(23) =86028558a(24) =196547581a(25) =449479587a(26) =1028674074a(27) =2356054490a(28) =5399827384a(29) =12383951473

External references