a(n) is the number of permutations of length n that have the same number of fixed points whether forwards or backwards.
A334830
a(n) is the number of permutations of length n that have the same number of fixed points whether forwards or backwards.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =0a(4) =14a(5) =46a(6) =200a(7) =1496a(8) =11718a(9) =111558a(10) =1052272a(11) =12261712a(12) =140348300a(13) =1915312460a(14) =25732919088a(15) =402510985872
External references
- oeis: A334830