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.

Previous Showing 11-18 of 18 results.

A323719 Array read by antidiagonals upwards where A(n, k) is the number of orderless factorizations of n with k - 1 levels of parentheses.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 4, 1, 1, 1, 1, 1, 3, 1, 5, 1, 1, 1, 1, 3, 1, 4, 1, 6, 1, 1, 1, 1, 2, 6, 1, 5, 1, 7, 1, 1, 1, 1, 2, 3, 10, 1, 6, 1, 8, 1, 1, 1, 1, 1, 3, 4, 15, 1, 7, 1, 9, 1, 1, 1, 1, 4, 1, 4, 5, 21, 1, 8, 1, 10, 1, 1, 1
Offset: 1

Views

Author

Gus Wiseman, Jan 25 2019

Keywords

Comments

An orderless factorization of n with k > 1 levels of parentheses is any multiset partition of an orderless factorization of n with k - 1 levels of parentheses. If k = 1 it is just an orderless factorization of n into factors > 1.

Examples

			Array begins:
       k=0  k=1  k=2  k=3  k=4  k=5  k=6  k=7  k=8  k=9  k=10 k=11 k=12
   n=1: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=2: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=3: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=4: 1    2    3    4    5    6    7    8    9   10   11   12   13
   n=5: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=6: 1    2    3    4    5    6    7    8    9   10   11   12   13
   n=7: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=8: 1    3    6   10   15   21   28   36   45   55   66   78   91
   n=9: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=10: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=11: 1    1    1    1    1    1    1    1    1    1    1    1    1
  n=12: 1    4    9   16   25   36   49   64   81  100  121  144  169
  n=13: 1    1    1    1    1    1    1    1    1    1    1    1    1
  n=14: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=15: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=16: 1    5   14   30   55   91  140  204  285  385  506  650  819
  n=17: 1    1    1    1    1    1    1    1    1    1    1    1    1
  n=18: 1    4    9   16   25   36   49   64   81  100  121  144  169
The A(12,3) = 16 orderless factorizations of 12 with 2 levels of parentheses:
  ((2*2*3))          ((2*6))      ((3*4))      ((12))
  ((2)*(2*3))        ((2)*(6))    ((3)*(4))
  ((3)*(2*2))        ((2))*((6))  ((3))*((4))
  ((2))*((2*3))
  ((2)*(2)*(3))
  ((3))*((2*2))
  ((2))*((2)*(3))
  ((3))*((2)*(2))
  ((2))*((2))*((3))
		

Crossrefs

Programs

  • Mathematica
    facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
    lev[n_,k_]:=If[k==0,{n},Join@@Table[Union[Sort/@Tuples[lev[#,k-1]&/@fac]],{fac,facs[n]}]];
    Table[Length[lev[sum-k,k]],{sum,12},{k,0,sum-1}]

A096807 Row sums of triangle A096806, in which the binomial transform of the n-th row lists the m-dimensional partitions of n, for n>=1 and m>=0.

Original entry on oeis.org

1, 2, 4, 10, 26, 78, 246, 844, 3062, 11782, 47664, 202254, 896462, 4139514
Offset: 1

Views

Author

Paul D. Hanna, Jul 19 2004

Keywords

Crossrefs

A116673 Row sums of triangle A116672, in which the binomial transform of the n-th row lists the Euler transform of the n-th sequence in A007318 (Pascal's Triangle).

Original entry on oeis.org

1, 2, 4, 10, 26, 80, 262, 950
Offset: 1

Views

Author

Alford Arnold, Feb 22 2006

Keywords

Comments

A116673 is to A096807 as Table A116672 is to Table A096806. The difference between the two tables is of historical interest. (cf. A096751 and A007326).

Examples

			A116672 begins
1; 1,1; 1,2,1; 1,4,4,1; 1,6,11,7,1; 1,10,27,29,12,1; 1,14,57,96,72,21,1; 1,21,117,277,319,176,38,1; . . . so
A116673 begins 1 2 4 10 26 80 262 950 ...
		

Crossrefs

A293551 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of exp(Sum_{j>=1} x^j/(j*(1 - x^j)^k)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 3, 1, 1, 1, 4, 6, 5, 1, 1, 1, 5, 10, 13, 7, 1, 1, 1, 6, 15, 26, 24, 11, 1, 1, 1, 7, 21, 45, 59, 48, 15, 1, 1, 1, 8, 28, 71, 120, 141, 86, 22, 1, 1, 1, 9, 36, 105, 216, 331, 310, 160, 30, 1, 1, 1, 10, 45, 148, 357, 672, 855, 692, 282, 42, 1, 1, 1, 11, 55, 201, 554, 1232, 1982, 2214, 1483, 500, 56, 1
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 11 2017

Keywords

Comments

A(n,k) is the Euler transform of j -> binomial(j+k-2,k-1) evaluated at n.

Examples

			Square array begins:
1,  1,   1,   1,    1,    1,  ...
1,  1,   1,   1,    1,    1,  ...
1,  2,   3,   4,    5,    6,  ...
1,  3,   6,  10,   15,   21,  ...
1,  5,  13,  26,   45,   71,  ...
1,  7,  24,  59,  120,  216,  ...
		

Crossrefs

Main diagonal gives A293554.
Cf. A007318, A096751 (a similar but different sequence).

Programs

  • Maple
    with(numtheory):
    A:= proc(n, k) option remember; `if`(n=0, 1, add(add(d*
          binomial(d+k-2, k-1), d=divisors(j))*A(n-j, k), j=1..n)/n)
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..14);  # Alois P. Heinz, Oct 17 2017
  • Mathematica
    Table[Function[k, SeriesCoefficient[E^(Sum[x^i/(i (1 - x^i)^k), {i, 1, n}]), {x, 0, n}]][j - n], {j, 0, 12}, {n, 0, j}] // Flatten

Formula

G.f. of column k: exp(Sum_{j>=1} x^j/(j*(1 - x^j)^k)).
For asymptotics of column k see comment from Vaclav Kotesovec in A255965.

A096802 Row sums of triangle A096801, which transforms the (n+m)-dimensional partitions of n into the (n+m+1)-dimensional partitions of n, for any fixed m.

Original entry on oeis.org

1, 1, 2, 4, 12, 42, 188, 950, 5362, 33361, 222120, 1600145, 12069976, 98105654
Offset: 0

Views

Author

Paul D. Hanna, Jul 13 2004

Keywords

Crossrefs

A096803 Column 1 of triangle A096801, which transforms the (n+m)-dimensional partitions of n into the (n+m+1)-dimensional partitions of n, for any fixed m.

Original entry on oeis.org

1, 1, 2, 7, 26, 124, 640, 3695, 23231, 156572, 1133838, 8635777, 70212042
Offset: 0

Views

Author

Paul D. Hanna, Jul 13 2004

Keywords

Crossrefs

A096805 Column 3 of triangle A096801, which transforms the (n+m)-dimensional partitions of n into the (n+m+1)-dimensional partitions of n, for any fixed m.

Original entry on oeis.org

1, 1, 4, 13, 68, 332, 2100, 12566, 94878, 623351, 5828851
Offset: 0

Views

Author

Paul D. Hanna, Jul 13 2004

Keywords

Crossrefs

A096804 Column 2 of triangle A096801, which transforms the (n+m)-dimensional partitions of n into the (n+m+1)-dimensional partitions of n, for any fixed m.

Original entry on oeis.org

1, 1, 3, 10, 44, 218, 1208, 7403, 48663, 346636, 2590866, 20875236
Offset: 0

Views

Author

Paul D. Hanna, Jul 13 2004

Keywords

Crossrefs

Previous Showing 11-18 of 18 results.