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.

Showing 1-3 of 3 results.

A286416 Number T(n,k) of entries in the k-th last blocks of all set partitions of [n]; triangle T(n,k), n>=1, 1<=k<=n, read by rows.

Original entry on oeis.org

1, 3, 1, 8, 6, 1, 24, 25, 10, 1, 83, 98, 63, 15, 1, 324, 399, 338, 135, 21, 1, 1400, 1746, 1727, 980, 257, 28, 1, 6609, 8271, 8874, 6426, 2455, 448, 36, 1, 33758, 42284, 47191, 40334, 20506, 5474, 730, 45, 1, 185136, 231939, 263458, 250839, 158827, 57239, 11128, 1128, 55, 1
Offset: 1

Views

Author

Alois P. Heinz, May 08 2017

Keywords

Examples

			T(3,2) = 6 because the number of entries in the second last blocks of all set partitions of [3] (123, 12|3, 13|2, 1|23, 1|2|3) is 0+2+2+1+1 = 6.
Triangle T(n,k) begins:
     1;
     3,    1;
     8,    6,    1;
    24,   25,   10,    1;
    83,   98,   63,   15,    1;
   324,  399,  338,  135,   21,   1;
  1400, 1746, 1727,  980,  257,  28,  1;
  6609, 8271, 8874, 6426, 2455, 448, 36, 1;
  ...
		

Crossrefs

Columns k=1-2 give: A038561 (for n>1), A286433.
Main diagonal and first lower diagonal give: A000012, A000217.
Row sums give A070071.

A285424 Sum of the entries in the last blocks of all set partitions of [n].

Original entry on oeis.org

1, 5, 19, 75, 323, 1512, 7630, 41245, 237573, 1451359, 9365361, 63604596, 453206838, 3378581609, 26285755211, 212953670251, 1792896572319, 15658150745252, 141619251656826, 1324477898999161, 12791059496663293, 127395689514237279, 1307010496324272157
Offset: 1

Views

Author

Alois P. Heinz, Apr 18 2017

Keywords

Examples

			a(3) = 19 because the sum of the entries in the last blocks of all set partitions of [3] (123, 12|3, 13|2, 1|23, 1|2|3) is 6+3+2+5+3 = 19.
		

Crossrefs

Column k=1 of A286232.

Programs

  • Maple
    a:= proc(h) option remember; local b; b:=
          proc(n, m, s) option remember; `if`(n=0, s,
            add(b(n-1, max(m, j), `if`(j
    				
  • Mathematica
    a[h_] := a[h] = Module[{b}, b[n_, m_, s_] := b[n, m, s] = If[n == 0, s,   Sum[b[n-1, Max[m, j], If[j < m, s, h - n + 1 + If[j == m, s, 0]]], {j, 1, m + 1}]]; b[h, 0, 0]];
    Array[a, 25] (* Jean-François Alcover, May 22 2018, translated from Maple *)

A286231 Sum T(n,k) of the entries in the k-th last cycles of all permutations of [n]; triangle T(n,k), n>=1, 1<=k<=n, read by rows.

Original entry on oeis.org

1, 5, 1, 25, 10, 1, 143, 79, 17, 1, 942, 634, 197, 26, 1, 7074, 5462, 2129, 417, 37, 1, 59832, 51214, 23381, 5856, 786, 50, 1, 563688, 523386, 269033, 80053, 13934, 1360, 65, 1, 5858640, 5813892, 3281206, 1111498, 232349, 29728, 2204, 82, 1
Offset: 1

Views

Author

Alois P. Heinz, May 04 2017

Keywords

Examples

			T(3,2) = 10 because the sum of the entries in the second last cycles of all permutations of [3] ((123), (132), (12)(3), (13)(2), (1)(23), (1)(2)(3)) is 0+0+3+4+1+2 = 10.
Triangle T(n,k) begins:
       1;
       5,      1;
      25,     10,      1;
     143,     79,     17,     1;
     942,    634,    197,    26,     1;
    7074,   5462,   2129,   417,    37,    1;
   59832,  51214,  23381,  5856,   786,   50,  1;
  563688, 523386, 269033, 80053, 13934, 1360, 65, 1;
  ...
		

Crossrefs

Column k=1 gives A285382.
Main diagonal and first lower diagonal give: A000012, A002522.
Row sums give A000142 * A000217 = A180119.
Showing 1-3 of 3 results.