Number of permutations of {1,2,...,n} having no increasing even cycles. A cycle (b(1), b(2), ...) is said to be increasing if, when written with its smallest element in the first position, it satisfies b(1)<b(2)<b(3)<... . A cycle is said to be even if it has an even number of entries.

A186765

Number of permutations of {1,2,...,n} having no increasing even cycles. A cycle (b(1), b(2), ...) is said to be increasing if, when written with its smallest element in the first position, it satisfies b(1)<b(2)<b(3)<... . A cycle is said to be even if it has an even number of entries.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =3a(4) =14a(5) =70a(6) =419a(7) =2933a(8) =23421a(9) =210789a(10) =2108144a(11) =23189584a(12) =278279165a(13) =3617629145a(14) =50646737049a(15) =759701055735

External references