Number of permutations of {1,2,...,n} having no nonincreasing odd 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 odd if it has an odd number of entries.
A186767
Number of permutations of {1,2,...,n} having no nonincreasing odd 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 odd if it has an odd number of entries.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =5a(4) =20a(5) =77a(6) =472a(7) =2585a(8) =21968a(9) =157113a(10) =1724064a(11) =15229645a(12) =204738624a(13) =2151199429a(14) =34194201472a(15) =416221515169
External references
- oeis: A186767