a(n) is the number of totally alternating permutations of 1,2,...,n.

A332345

a(n) is the number of totally alternating permutations of 1,2,...,n.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =6a(5) =12a(6) =28a(7) =76a(8) =240a(9) =852a(10) =3392a(11) =14868a(12) =71392a(13) =371740a(14) =2089184a(15) =12589980a(16) =81037792a(17) =554555300a(18) =4021728992a(19) =30800978980a(20) =248464000480

External references