1/3 of the number of permutations of 2 indistinguishable copies of 1..n with exactly 2 local maxima.
A152494
1/3 of the number of permutations of 2 indistinguishable copies of 1..n with exactly 2 local maxima.
Terms
- a(0) =0a(1) =1a(2) =19a(3) =235a(4) =2539a(5) =26119a(6) =263863a(7) =2648107a(8) =26513875a(9) =265250287a(10) =2652876847a(11) =26530008499a(12) =265304159371
External references
- oeis: A152494