Number of fixed points in all reverse alternating (i.e., up-down) permutations of {1,2,...,n}.
A162977
Number of fixed points in all reverse alternating (i.e., up-down) permutations of {1,2,...,n}.
Terms
- a(0) =1a(1) =2a(2) =1a(3) =4a(4) =15a(5) =62a(6) =257a(7) =1384a(8) =7679a(9) =50522a(10) =346113a(11) =2702764a(12) =22022143a(13) =199360982a(14) =1881735169a(15) =19391512144a(16) =207983607807
External references
- oeis: A162977