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 1-4 of 4 results.

A327631 Number T(n,k) of parts in all proper k-times partitions of n; triangle T(n,k), n >= 1, 0 <= k <= n-1, read by rows.

Original entry on oeis.org

1, 1, 2, 1, 5, 3, 1, 11, 21, 12, 1, 19, 61, 74, 30, 1, 34, 205, 461, 432, 144, 1, 53, 474, 1652, 2671, 2030, 588, 1, 85, 1246, 6795, 17487, 23133, 15262, 3984, 1, 127, 2723, 20966, 76264, 148134, 158452, 88194, 19980, 1, 191, 6277, 69812, 360114, 1002835, 1606434, 1483181, 734272, 151080
Offset: 1

Views

Author

Alois P. Heinz, Sep 19 2019

Keywords

Comments

In each step at least one part is replaced by the partition of itself into smaller parts. The parts are not resorted.
T(n,k) is defined for all n>=0 and k>=0. The triangle displays only positive terms. All other terms are zero.
Row n is the inverse binomial transform of the n-th row of array A327618.

Examples

			T(4,0) = 1:
  4    (1 part).
T(4,1) = 11 = 2 + 2 + 3 + 4:
  4-> 31    (2 parts)
  4-> 22    (2 parts)
  4-> 211   (3 parts)
  4-> 1111  (4 parts)
T(4,2) = 21 = 3 + 4 + 3 + 3 + 4 + 4:
  4-> 31 -> 211   (3 parts)
  4-> 31 -> 1111  (4 parts)
  4-> 22 -> 112   (3 parts)
  4-> 22 -> 211   (3 parts)
  4-> 22 -> 1111  (4 parts)
  4-> 211-> 1111  (4 parts)
T(4,3) = 12 = 4 + 4 + 4:
  4-> 31 -> 211 -> 1111  (4 parts)
  4-> 22 -> 112 -> 1111  (4 parts)
  4-> 22 -> 211 -> 1111  (4 parts)
Triangle T(n,k) begins:
  1;
  1,   2;
  1,   5,    3;
  1,  11,   21,    12;
  1,  19,   61,    74,    30;
  1,  34,  205,   461,   432,    144;
  1,  53,  474,  1652,  2671,   2030,    588;
  1,  85, 1246,  6795, 17487,  23133,  15262,  3984;
  1, 127, 2723, 20966, 76264, 148134, 158452, 88194, 19980;
  ...
		

Crossrefs

Columns k=0-2 give: A057427, -1+A006128(n), A328042.
Row sums give A327648.
T(n,floor(n/2)) gives A328041.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, [1, 0],
         `if`(k=0, [1, 1], `if`(i<2, 0, b(n, i-1, k))+
             (h-> (f-> f +[0, f[1]*h[2]/h[1]])(h[1]*
            b(n-i, min(n-i, i), k)))(b(i$2, k-1))))
        end:
    T:= (n, k)-> add(b(n$2, i)[2]*(-1)^(k-i)*binomial(k, i), i=0..k):
    seq(seq(T(n, k), k=0..n-1), n=1..12);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, {1, 0}, If[k == 0, {1, 1}, If[i < 2, 0, b[n, i - 1, k]] + Function[h, Function[f, f + {0, f[[1]]*h[[2]]/ h[[1]]}][h[[1]]*b[n - i, Min[n - i, i], k]]][b[i, i, k - 1]]]];
    T[n_, k_] := Sum[b[n, n, i][[2]]*(-1)^(k - i)*Binomial[k, i], {i, 0, k}];
    Table[T[n, k], {n, 1, 12}, {k, 0, n - 1}] // Flatten (* Jean-François Alcover, Jan 07 2020, after Alois P. Heinz *)

Formula

T(n,k) = Sum_{i=0..k} (-1)^(k-i) * binomial(k,i) * A327618(n,i).
T(n,n-1) = n * A327639(n,n-1) = n * A327643(n) for n >= 1.

A327622 Number A(n,k) of parts in all k-times partitions of n into distinct parts; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 3, 1, 0, 1, 1, 5, 3, 1, 0, 1, 1, 7, 8, 5, 1, 0, 1, 1, 9, 16, 15, 8, 1, 0, 1, 1, 11, 27, 35, 28, 10, 1, 0, 1, 1, 13, 41, 69, 73, 49, 13, 1, 0, 1, 1, 15, 58, 121, 160, 170, 86, 18, 1, 0, 1, 1, 17, 78, 195, 311, 460, 357, 156, 25, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 19 2019

Keywords

Comments

Row n is binomial transform of the n-th row of triangle A327632.

Examples

			Square array A(n,k) begins:
  0,  0,  0,   0,    0,    0,    0,     0,     0, ...
  1,  1,  1,   1,    1,    1,    1,     1,     1, ...
  1,  1,  1,   1,    1,    1,    1,     1,     1, ...
  1,  3,  5,   7,    9,   11,   13,    15,    17, ...
  1,  3,  8,  16,   27,   41,   58,    78,   101, ...
  1,  5, 15,  35,   69,  121,  195,   295,   425, ...
  1,  8, 28,  73,  160,  311,  553,   918,  1443, ...
  1, 10, 49, 170,  460, 1047, 2106,  3865,  6611, ...
  1, 13, 86, 357, 1119, 2893, 6507, 13182, 24625, ...
		

Crossrefs

Columns k=0-3 give: A057427, A015723, A327605, A327628.
Rows n=0,(1+2),3-5 give: A000004, A000012, A005408, A104249, A005894.
Main diagonal gives: A327623.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, [1, 0],
         `if`(k=0, [1, 1], `if`(i*(i+1)/2 (f-> f +[0, f[1]*h[2]/h[1]])(h[1]*
            b(n-i, min(n-i, i-1), k)))(b(i$2, k-1)))))
        end:
    A:= (n, k)-> b(n$2, k)[2]:
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = With[{}, If[n==0, Return@{1, 0}]; If[k == 0, Return@{1, 1}]; If[i(i + 1)/2 < n, Return@{0, 0}]; b[n, i - 1, k] + Function[h, Function[f, f + {0, f[[1]] h[[2]]/h[[1]]}][h[[1]] b[n - i, Min[n - i, i - 1], k]]][b[i, i, k - 1]]];
    A[n_, k_] := b[n, n, k][[2]];
    Table[A[n, d - n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, Jun 03 2020, after Maple *)

Formula

A(n,k) = Sum_{i=0..k} binomial(k,i) * A327632(n,i).

A327647 Number of parts in all proper many times partitions of n into distinct parts.

Original entry on oeis.org

0, 1, 1, 3, 6, 15, 38, 133, 446, 1913, 7492, 36293, 175904, 953729, 5053294, 31353825, 188697696, 1268175779, 8356974190, 61775786301, 448436391810, 3579695446911, 27848806031468, 239229189529685, 2019531300063238, 18477179022470655, 165744369451885256
Offset: 0

Views

Author

Alois P. Heinz, Sep 20 2019

Keywords

Comments

In each step at least one part is replaced by the partition of itself into smaller distinct parts. The parts are not resorted and the parts in the result are not necessarily distinct.

Examples

			a(4) = 6 = 1 + 2 + 3, counting the (final) parts in 4, 4->31, 4->31->211.
		

Crossrefs

Row sums of A327632, A327648.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, [1, 0],
         `if`(k=0, [1, 1], `if`(i*(i+1)/2 (f-> f +[0, f[1]*h[2]/h[1]])(h[1]*
            b(n-i, min(n-i, i-1), k)))(b(i$2, k-1)))))
        end:
    a:= n-> add(add(b(n$2, i)[2]*(-1)^(k-i)*
            binomial(k, i), i=0..k), k=0..max(0, n-2)):
    seq(a(n), n=0..27);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, {1, 0}, If[k == 0, {1, 1}, If[i(i + 1)/2 < n, 0, b[n, i - 1, k] + Function[h, Function[f, f + {0, f[[1]]* h[[2]]/h[[1]]}][h[[1]] b[n-i, Min[n - i, i - 1], k]]][b[i, i, k - 1]]]]];
    a[n_] := Sum[Sum[b[n, n, i][[2]] (-1)^(k-i) Binomial[k, i], {i, 0, k}], {k, 0, Max[0, n-2]}];
    a /@ Range[0, 27] (* Jean-François Alcover, May 03 2020, after Maple *)

A327795 Number of parts in all proper twice partitions of n into distinct parts.

Original entry on oeis.org

0, 0, 0, 3, 6, 13, 30, 61, 121, 210, 353, 600, 989, 1628, 2667, 4205, 6514, 10406, 15893, 24322, 37516, 56824, 85102, 128420, 191579, 284898, 422839, 622721, 913006, 1345320, 1958269, 2843788, 4140170, 5983662, 8632808, 12433730, 17830728, 25527909, 36516161
Offset: 1

Views

Author

Alois P. Heinz, Sep 25 2019

Keywords

Examples

			a(4) = 3:
  4 -> 31 -> 211   (3 parts)
		

Crossrefs

Column k=2 of A327632.
Cf. A327605.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, [1, 0],
         `if`(k=0, [1, 1], `if`(i*(i+1)/2 (f-> f +[0, f[1]*h[2]/h[1]])(h[1]*
            b(n-i, min(n-i, i-1), k)))(b(i$2, k-1)))))
        end:
    a:= n-> (k-> add(b(n$2, i)[2]*(-1)^(k-i)*binomial(k, i), i=0..k))(2):
    seq(a(n), n=1..41);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = With[{}, If[n == 0, {1, 0}, If[k == 0, {1, 1}, If[i (i + 1)/2 < n, {0, 0}, b[n, i - 1, k] + Function[h, Function[f, f + {0, f[[1]] h[[2]]/h[[1]]}][h[[1]] b[n - i, Min[n - i, i - 1], k]]][ b[i, i, k - 1]]]]]];
    T[n_, k_] := Sum[b[n, n, i][[2]] (-1)^(k - i) Binomial[k, i], {i, 0, k}];
    a[n_] := T[n, 2];
    Array[a, 41] (* Jean-François Alcover, Dec 09 2020, after Alois P. Heinz *)
Showing 1-4 of 4 results.