OFFSET
1,2
COMMENTS
Row sums are n!*n = A001563(n) (see example).
For fixed k>=1, A185105(n,k) ~ n!*n/2^k. - Vaclav Kotesovec, Apr 25 2017
LINKS
Alois P. Heinz, Rows n = 1..141, flattened
Wikipedia, Permutation
EXAMPLE
The six permutations of n=3 in ordered cycle form are:
{ {1}, {2}, {3} }
{ {1}, {2, 3}, {} }
{ {1, 2}, {3}, {} }
{ {1, 2, 3}, {}, {}}
{ {1, 3, 2}, {}, {}}
{ {1, 3}, {2}, {} }
.
The lengths of the cycles in position k=1 sum to 12, those of the cycles in position k=2 sum to 5 and those of the cycles in position k=3 sum to 1.
Triangle begins:
1;
3, 1;
12, 5, 1;
60, 27, 8, 1;
360, 168, 59, 12, 1;
2520, 1200, 463, 119, 17, 1;
20160, 9720, 3978, 1177, 221, 23, 1;
181440, 88200, 37566, 12217, 2724, 382, 30, 1;
...
MAPLE
b:= proc(n, i) option remember; expand(`if`(n=0, 1,
add((p-> p+coeff(p, x, 0)*j*x^i)(b(n-j, i+1))*
binomial(n-1, j-1)*(j-1)!, j=1..n)))
end:
T:= n-> (p-> seq(coeff(p, x, i), i=1..n))(b(n, 1)):
seq(T(n), n=1..12); # Alois P. Heinz, Apr 15 2017
MATHEMATICA
Table[it = Join[RotateRight /@ ToCycles[#], Table[{}, {k}]] & /@ Permutations[Range[n]]; Tr[Length[Part[#, k]]& /@ it], {n, 7}, {k, n}]
(* Second program: *)
b[n_, i_] := b[n, i] = Expand[If[n==0, 1, Sum[Function[p, p + Coefficient[ p, x, 0]*j*x^i][b[n-j, i+1]]*Binomial[n-1, j-1]*(j-1)!, {j, 1, n}]]];
T[n_] := Function[p, Table[Coefficient[p, x, i], {i, 1, n}]][b[n, 1]];
Array[T, 12] // Flatten (* Jean-François Alcover, May 30 2018, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Wouter Meeussen, Dec 26 2012
EXTENSIONS
More terms from Alois P. Heinz, Apr 15 2017
STATUS
approved