Irregular triangle read by rows: T(n,k) = number of size k subsets of S_n that remain unchanged under the operation of replacing a permutation with its inverse.
A277081
Irregular triangle read by rows: T(n,k) = number of size k subsets of S_n that remain unchanged under the operation of replacing a permutation with its inverse.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =1a(7) =1a(8) =4a(9) =7a(10) =8a(11) =7a(12) =4a(13) =1a(14) =1a(15) =10a(16) =52a(17) =190a(18) =546a(19) =1302a(20) =2660a(21) =4754a(22) =7535a(23) =10692a(24) =13672a(25) =15820a(26) =16604a(27) =15820a(28) =13672a(29) =10692
External references
- oeis: A277081