cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A322383 Number T(n,k) of entries in the k-th cycles of all permutations of [n] when cycles are ordered by increasing lengths (and increasing smallest elements); triangle T(n,k), n>=1, 1<=k<=n, read by rows.

Original entry on oeis.org

1, 3, 1, 10, 7, 1, 45, 37, 13, 1, 236, 241, 101, 21, 1, 1505, 1661, 896, 226, 31, 1, 10914, 13301, 7967, 2612, 442, 43, 1, 90601, 117209, 78205, 29261, 6441, 785, 57, 1, 837304, 1150297, 827521, 346453, 88909, 14065, 1297, 73, 1, 8610129, 12314329, 9507454, 4338214, 1253104, 234646, 28006, 2026, 91, 1
Offset: 1

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Author

Alois P. Heinz, Dec 05 2018

Keywords

Examples

			The 6 permutations of {1,2,3} are:
  (1)     (2)   (3)
  (1)     (2,3)
  (2)     (1,3)
  (3)     (1,2)
  (1,2,3)
  (1,3,2)
so there are 10 elements in the first cycles, 7 in the second cycles and only 1 in the third cycles.
Triangle T(n,k) begins:
      1;
      3,      1;
     10,      7,     1;
     45,     37,    13,     1;
    236,    241,   101,    21,    1;
   1505,   1661,   896,   226,   31,   1;
  10914,  13301,  7967,  2612,  442,  43,  1;
  90601, 117209, 78205, 29261, 6441, 785, 57, 1;
  ...
		

Crossrefs

Row sums give A001563.

Programs

  • Maple
    b:= proc(n, l) option remember; `if`(n=0, add(l[i]*
          x^i, i=1..nops(l)), add(binomial(n-1, j-1)*
          b(n-j, sort([l[], j]))*(j-1)!, j=1..n))
        end:
    T:= n-> (p-> (seq(coeff(p, x, i), i=1..n)))(b(n, [])):
    seq(T(n), n=1..12);
  • Mathematica
    b[n_, l_] := b[n, l] = If[n == 0, l.x^Range[Length[l]], Sum[Binomial[n - 1, j - 1] b[n - j, Sort[Append[l, j]]] (j - 1)!, {j, 1, n}]];
    T[n_] := Rest @ CoefficientList[b[n, {}], x];
    Array[T, 12] // Flatten (* Jean-François Alcover, Mar 03 2020, after Alois P. Heinz *)