Number of permutations of 1,...,n with at least one pair of adjacent consecutive entries (i.e., of the form k(k+1) or (k+1)k), n >= 2.

A129535

Number of permutations of 1,...,n with at least one pair of adjacent consecutive entries (i.e., of the form k(k+1) or (k+1)k), n >= 2.

Terms

    a(0) =2a(1) =6a(2) =22a(3) =106a(4) =630a(5) =4394a(6) =35078a(7) =315258a(8) =3149494a(9) =34620010a(10) =415222566a(11) =5395737242a(12) =75516784982

External references