A306535
Number of permutations p of [2n] having no index i with |p(i)-i| = n.
Original entry on oeis.org
1, 1, 9, 265, 14833, 1334961, 176214841, 32071101049, 7697064251745, 2355301661033953, 895014631192902121, 413496759611120779881, 228250211305338670494289, 148362637348470135821287825, 112162153835443422680893595673, 97581073836835777732377428235481
Offset: 0
-
b:= proc(n, k) b(n, k):= `if`(k=0, n!, b(n+1, k-1) -b(n, k-1)) end:
a:= n-> b(0, 2*n):
seq(a(n), n=0..23);
seq(simplify(KummerU(-2*n, -2*n, -1)), n=0..15); # Peter Luschny, May 10 2022
-
b[n_, k_] := b[n, k] = If[k == 0, n!, b[n + 1, k - 1] - b[n, k - 1]];
a[n_] := b[0, 2n];
a /@ Range[0, 23] (* Jean-François Alcover, Apr 02 2021, after Alois P. Heinz *)
A116854
First differences of the rows in the triangle of A116853, starting with 0.
Original entry on oeis.org
1, 1, 1, 3, 1, 2, 11, 3, 4, 6, 53, 11, 14, 18, 24, 309, 53, 64, 78, 96, 120, 2119, 309, 362, 426, 504, 600, 720, 16687, 2119, 2428, 2790, 3216, 3720, 4320, 5040, 148329, 16687, 18806, 21234, 24024, 27240, 30960, 35280, 40320, 1468457, 148329, 165016, 183822, 205056, 229080, 256320, 287280, 322560, 362880
Offset: 1
First few rows of the triangle are:
[1] 1;
[2] 1, 1;
[3] 3, 1, 2;
[4] 11, 3, 4, 6;
[5] 53, 11, 14, 18, 24;
[6] 309, 53, 64, 78, 96, 120;
[7] 2119, 309, 362, 426, 504, 600, 720;
...
For example, row 4 (11, 3, 4, 6) are first differences along row 4 of A116853: ((0), 11, 14, 18, 24).
-
a116854 n k = a116854_tabl !! (n-1) !! (k-1)
a116854_row n = a116854_tabl !! (n-1)
a116854_tabl = [1] : zipWith (:) (tail $ map head tss) tss
where tss = a116853_tabl
-- Reinhard Zumkeller, Aug 31 2014
-
A116853 := proc(n,k) option remember ; if n = k then n! ; else procname(n,k+1)-procname(n-1,k) ; end if; end proc:
A116854 := proc(n,k) if k = 1 then A116853(n,1) ; else A116853(n,k) -A116853(n,k-1) ; end if; end proc:
seq(seq(A116854(n,k),k=1..n),n=1..15) ; # R. J. Mathar, Mar 27 2010
-
rows = 10;
rr = Range[rows]!;
dd = Table[Differences[rr, n], {n, 0, rows - 1}];
T = Array[t, {rows, rows}];
Do[Thread[Evaluate[Diagonal[T, -k+1]] = dd[[k, ;; rows-k+1]]], {k, rows}];
Table[({0}~Join~Table[t[n, k], {k, 1, n}]) // Differences, {n, 1, rows}] // Flatten (* Jean-François Alcover, Dec 21 2019 *)
Definition made concrete and sequence extended by
R. J. Mathar, Mar 27 2010
Comments