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.

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.

A327644 Number of proper many times partitions of n.

Original entry on oeis.org

1, 1, 2, 4, 14, 44, 244, 1196, 9366, 62296, 584016, 5120548, 60244028, 627389924, 8378159376, 106097674780, 1652301306958, 23655318730276, 409987534384504, 6742903763089068, 130675390985884516, 2396246933608687036, 50636625943991790784, 1032841246318579471748
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 parts. The parts are not resorted.

Examples

			a(3) = 4: 3, 3->21, 3->111, 3->21->111.
a(4) = 14: 4, 4->31, 4->22, 4->211, 4->1111, 4->31->211, 4->31->1111, 4->22->112, 4->22->211, 4->22->1111, 4->211->1111, 4->31->211->1111, 4->22->112->1111, 4->22->211->1111.
		

Crossrefs

Row sums of A327639.
Cf. A327648.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or k=0, 1, `if`(i>1,
          b(n, i-1, k), 0) +b(i$2, k-1)*b(n-i, min(n-i, i), k))
        end:
    a:= n-> add(add(b(n$2, i)*(-1)^(k-i)*
            binomial(k, i), i=0..k), k=0..max(0, n-1)):
    seq(a(n), n=0..23);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || k == 0, 1, If[i > 1, b[n, i - 1, k], 0] + b[i, i, k - 1] b[n - i, Min[n - i, i], k]];
    a[n_] := Sum[b[n, n, i] (-1)^(k - i) Binomial[k, i], {k, 0, Max[0, n - 1]}, {i, 0, k}];
    a /@ Range[0, 23] (* Jean-François Alcover, Dec 09 2020, after Alois P. Heinz *)

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 *)
Showing 1-3 of 3 results.