Triangle read by rows: T(n,k) is one-half the number of permutations of length n with exactly n-k rising or falling successions, for n >= 1, 1 <= k <= n. T(1,1) = 1 by convention.
A010028
Triangle read by rows: T(n,k) is one-half the number of permutations of length n with exactly n-k rising or falling successions, for n >= 1, 1 <= k <= n. T(1,1) = 1 by convention.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =1a(4) =2a(5) =0a(6) =1a(7) =5a(8) =5a(9) =1a(10) =1a(11) =8a(12) =24a(13) =20a(14) =7a(15) =1a(16) =11a(17) =60a(18) =128a(19) =115a(20) =45a(21) =1a(22) =14a(23) =113a(24) =444a(25) =835a(26) =790a(27) =323a(28) =1a(29) =17
External references
- oeis: A010028