Triangle read by rows: T(n,k) is the number of permutations of [n] starting with 1, having no 3-sequences and having k successions (0 <= k <= floor(n/2)); a succession of a permutation p is a position i such that p(i +1) - p(i) = 1.
A180186
Triangle read by rows: T(n,k) is the number of permutations of [n] starting with 1, having no 3-sequences and having k successions (0 <= k <= floor(n/2)); a succession of a permutation p is a position i such that p(i +1) - p(i) = 1.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =1a(4) =1a(5) =0a(6) =2a(7) =3a(8) =0a(9) =9a(10) =8a(11) =3a(12) =44a(13) =45a(14) =12a(15) =1a(16) =265a(17) =264a(18) =90a(19) =8a(20) =1854a(21) =1855a(22) =660a(23) =90a(24) =2a(25) =14833a(26) =14832a(27) =5565a(28) =880a(29) =45
External references
- oeis: A180186