Number of ordered pairs (p,q) of permutations of [n] with complementary up-down signatures and p(1)=q(1) if n>0.

A262241

Number of ordered pairs (p,q) of permutations of [n] with complementary up-down signatures and p(1)=q(1) if n>0.

Terms

    a(0) =1a(1) =1a(2) =0a(3) =2a(4) =12a(5) =144a(6) =2456a(7) =58376a(8) =1836064a(9) =73967072a(10) =3714221440a(11) =227511703296

External references