Number of permutations where for every pair of adjacent elements one element in binary notation has ones at the same or adjacent positions to those of the other element.

A115508

Number of permutations where for every pair of adjacent elements one element in binary notation has ones at the same or adjacent positions to those of the other element.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =4a(4) =4a(5) =40a(6) =120a(7) =72a(8) =140a(9) =824a(10) =3312a(11) =22320a(12) =110976a(13) =1369536a(14) =9477120a(15) =3596160a(16) =3235584a(17) =36927360a(18) =286846848a(19) =700001376a(20) =3321184800a(21) =41563274304a(22) =279121008576

External references