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 A344855 Number T(n,k) of permutations of [n] having k cycles of the form (c1, c2, ..., c_m) where c1 = min_{i>=1} c_i and c_j = min_{i>=j} c_i or c_j = max_{i>=j} c_i; triangle T(n,k), n>=0, 0<=k<=n, read by rows. 13
 1, 0, 1, 0, 1, 1, 0, 2, 3, 1, 0, 4, 11, 6, 1, 0, 8, 40, 35, 10, 1, 0, 16, 148, 195, 85, 15, 1, 0, 32, 560, 1078, 665, 175, 21, 1, 0, 64, 2160, 5992, 5033, 1820, 322, 28, 1, 0, 128, 8448, 33632, 37632, 17913, 4284, 546, 36, 1, 0, 256, 33344, 190800, 280760, 171465, 52941, 9030, 870, 45, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,8 COMMENTS The sequence of column k satisfies a linear recurrence with constant coefficients of order k*(k+1)/2 = A000217(k). LINKS Alois P. Heinz, Rows n = 0..140, flattened Wikipedia, Permutation FORMULA Sum_{k=1..n} k * T(n,k) = A345341(n). For fixed k, T(n,k) ~ (2*k)^n / (4^k * k!). - Vaclav Kotesovec, Jul 15 2021 EXAMPLE T(4,1) = 4: (1234), (1243), (1423), (1432). Triangle T(n,k) begins: 1; 0, 1; 0, 1, 1; 0, 2, 3, 1; 0, 4, 11, 6, 1; 0, 8, 40, 35, 10, 1; 0, 16, 148, 195, 85, 15, 1; 0, 32, 560, 1078, 665, 175, 21, 1; 0, 64, 2160, 5992, 5033, 1820, 322, 28, 1; ... MAPLE b:= proc(n) option remember; `if`(n=0, 1, add(expand(x* b(n-j)*binomial(n-1, j-1)*ceil(2^(j-2))), j=1..n)) end: T:= n-> (p-> seq(coeff(p, x, i), i=0..n))(b(n)): seq(T(n), n=0..12); MATHEMATICA b[n_] := b[n] = If[n == 0, 1, Sum[Expand[x*b[n-j]* Binomial[n-1, j-1]*Ceiling[2^(j-2)]], {j, n}]]; T[n_] := CoefficientList[b[n], x]; Table[T[n], {n, 0, 12}] // Flatten (* Jean-François Alcover, Aug 23 2021, after Alois P. Heinz *) CROSSREFS Columns k=0-10 give: A000007, A166444, A346317, A346318, A346319, A346320, A346321, A346322, A346323, A346324, A346325. Row sums give A187251. Main diagonal gives A000012, lower diagonal gives A000217, second lower diagonal gives A000914. T(n+1,n) gives A000217. T(n+2,n) gives A000914. T(2n,n) gives A345342. Cf. A060281, A132393, A186366, A345341. Sequence in context: A100329 A193535 A332645 * A081247 A298753 A173050 Adjacent sequences: A344852 A344853 A344854 * A344856 A344857 A344858 KEYWORD nonn,tabl AUTHOR Alois P. Heinz, May 30 2021 STATUS approved

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Last modified June 20 07:26 EDT 2024. Contains 373512 sequences. (Running on oeis4.)