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 1-5 of 5 results.

A292463 Number of partitions of n with n kinds of 1.

Original entry on oeis.org

1, 1, 4, 14, 51, 188, 702, 2644, 10026, 38223, 146359, 562456, 2168134, 8379539, 32459199, 125984039, 489837300, 1907490728, 7438346255, 29042470132, 113522618066, 444199913556, 1739735079466, 6819657196928, 26753893533257, 105034060120469, 412637434996367
Offset: 0

Views

Author

Alois P. Heinz, Sep 16 2017

Keywords

Examples

			a(2) = 4: 2, 1a1a, 1a1b, 1b1b.
		

Crossrefs

Main diagonal of A292508.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2,
          binomial(k+n-1, n), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> b(n$3):
    seq(a(n), n=0..30);
    # second Maple program:
    b:= proc(n, k) option remember; `if`(n=0, 1, add(
          (numtheory[sigma](j)+k-1)*b(n-j, k), j=1..n)/n)
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..30);
    # third Maple program:
    b:= proc(n, k) option remember; `if`(n=0, 1, `if`(k=1,
          combinat[numbpart](n), b(n-1, k) +b(n, k-1)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..30);
  • Mathematica
    Table[SeriesCoefficient[1/(1-x)^(n-1) * Product[1/(1-x^k), {k,1,n}], {x,0,n}], {n,0,30}] (* Vaclav Kotesovec, Sep 19 2017 *)

Formula

a(n) = [x^n] 1/(1-x)^n * 1/Product_{j=2..n} (1-x^j).
a(n) is n-th term of the Euler transform of n,1,1,1,... .
a(n) ~ c * 4^n / sqrt(n), where c = QPochhammer[-1, 1/2] / (8*sqrt(Pi) * QPochhammer[1/4, 1/4]) = 0.48841139329043831428669851139824427133317... - Vaclav Kotesovec, Sep 19 2017
Equivalently, c = 1/(4*sqrt(Pi)*QPochhammer(1/2)). - Vaclav Kotesovec, Mar 17 2024

A292503 Number of partitions of n with n sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 1, 3, 7, 20, 63, 233, 966, 4454, 22404, 121616, 706362, 4361977, 28494493, 196087988, 1416515642, 10709058487, 84505818259, 694397612486, 5929368380664, 52513737017847, 481577858196052, 4565851595293151, 44692014464166068, 451058715629365617
Offset: 0

Views

Author

Alois P. Heinz, Sep 17 2017

Keywords

Examples

			a(2) = 3: 2, 1a1a, 1a1b.
a(3) = 7: 3, 21a, 1a1a1a, 1a1a1b, 1a1b1a, 1a1b1b, 1a1b1c.
		

Crossrefs

Main diagonal of A292745.
Row sums of A292746.

Programs

  • Maple
    f:= (n, k)-> add(Stirling2(n, j), j=0..k):
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2,
          f(n, k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> b(n$3):
    seq(a(n), n=0..30);
  • Mathematica
    f[n_, k_] := Sum[StirlingS2[n, j], {j, 0, k}];
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i < 2, f[n, k], Sum[b[n - i*j, i - 1, k], {j, 0, n/i}]];
    a[n_] := b[n, n, n];
    Table[a[n], {n, 0, 30}] (* Jean-François Alcover, May 17 2018, translated from Maple *)

A292741 Number A(n,k) of partitions of n with k sorts of part 1; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 2, 2, 1, 1, 3, 5, 3, 2, 1, 4, 10, 11, 5, 2, 1, 5, 17, 31, 24, 7, 4, 1, 6, 26, 69, 95, 50, 11, 4, 1, 7, 37, 131, 278, 287, 104, 15, 7, 1, 8, 50, 223, 657, 1114, 865, 212, 22, 8, 1, 9, 65, 351, 1340, 3287, 4460, 2599, 431, 30, 12, 1, 10, 82, 521, 2459, 8042, 16439, 17844, 7804, 870, 42, 14
Offset: 0

Views

Author

Alois P. Heinz, Sep 22 2017

Keywords

Examples

			A(1,3) = 3: 1a, 1b, 1c.
A(2,3) = 10: 2, 1a1a, 1a1b, 1a1c, 1b1a, 1b1b, 1b1c, 1c1a, 1c1b, 1c1c.
A(3,2) = 11: 3, 21a, 21b, 1a1a1a, 1a1a1b, 1a1b1a, 1a1b1b, 1b1a1a, 1b1a1b, 1b1b1a, 1b1b1b.
Square array A(n,k) begins:
  1,  1,   1,    1,     1,     1,      1,      1, ...
  0,  1,   2,    3,     4,     5,      6,      7, ...
  1,  2,   5,   10,    17,    26,     37,     50, ...
  1,  3,  11,   31,    69,   131,    223,    351, ...
  2,  5,  24,   95,   278,   657,   1340,   2459, ...
  2,  7,  50,  287,  1114,  3287,   8042,  17215, ...
  4, 11, 104,  865,  4460, 16439,  48256, 120509, ...
  4, 15, 212, 2599, 17844, 82199, 289540, 843567, ...
		

Crossrefs

Columns k=0-2 give: A002865, A000041, A090764.
Rows n=0-2 give: A000012, A001477, A002522, A071568.
Main diagonal gives A292462.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, k^n,
          add(b(n-i*j, i-1, k), j=0..iquo(n, i)))
        end:
    A:= (n, k)-> b(n$2, k):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    b[0, , ] = 1; b[n_, i_, k_] := b[n, i, k] = If[i < 2, k^n, Sum[b[n - i*j, i - 1, k], {j, 0, Quotient[n, i]}]];
    A[n_, k_] := b[n, n, k];
    Table[A[n, d - n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, May 19 2018, translated from Maple *)

Formula

G.f. of column k: 1/(1-k*x) * 1/Product_{j>=2} (1-x^j).
A(n,k) = Sum_{j=0..n} A002865(j) * k^(n-j).

A292507 Number of partitions of n with up to n distinct kinds of 1.

Original entry on oeis.org

1, 1, 2, 5, 13, 33, 82, 201, 488, 1176, 2817, 6714, 15931, 37647, 88628, 207914, 486158, 1133304, 2634339, 6106953, 14121157, 32573842, 74968044, 172164086, 394561089, 902471184, 2060338222, 4695324425, 10681885697, 24261437446, 55017434305, 124573678280
Offset: 0

Views

Author

Alois P. Heinz, Sep 17 2017

Keywords

Examples

			a(3) = 5: 3, 21a, 21b, 21c, 1a1b1c.
a(4) = 13: 4, 31a, 31b, 31c, 31d, 22, 21a1b, 21a1c, 21a1d, 21b1c, 21b1d, 21c1d, 1a1b1c1d.
		

Crossrefs

Main diagonal of A292622.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1,
          binomial(k, n), `if`(i>n, 0, b(n-i, i, k))+b(n, i-1, k))
        end:
    a:= n-> b(n$3):
    seq(a(n), n=0..35);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i == 1, Binomial[k, n], If[i > n, 0, b[n - i, i, k]] + b[n, i - 1, k]];
    a[n_] := b[n, n, n];
    Table[a[n], {n, 0, 35}] (* Jean-François Alcover, May 20 2018, translated from Maple *)

Formula

Conjecture: log(a(n)) ~ log(2)*n + Pi*sqrt(n/3) - 3*log(n)/2. - Vaclav Kotesovec, May 11 2019
a(n) = [x^n] (1 + x)^n * Product_{k>=2} 1 / (1 - x^k). - Ilya Gutkovskiy, Apr 24 2021

A292567 a(n) = [x^n] 1/(1+n*x) * Product_{j=2..n} 1/(1-x^j).

Original entry on oeis.org

1, -1, 5, -29, 270, -3233, 47800, -838561, 17013991, -391779640, 10091836632, -287491284748, 8973657413421, -304549220113387, 11165193890312790, -439726629957500944, 18514829984975265703, -829953080825411342745, 39461813340364709540008
Offset: 0

Views

Author

Alois P. Heinz, Sep 19 2017

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, (-k)^n,
          `if`(i>n, 0, b(n-i, i, k))+b(n, i-1, k))
        end:
    a:= n-> b(n$3):
    seq(a(n), n=0..23);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i == 1, (-k)^n, If[i > n, 0, b[n - i, i, k]] + b[n, i - 1, k]];
    a[n_] := If[n == 0, 1, b[n, n, n]];
    a /@ Range[0, 23] (* Jean-François Alcover, Dec 30 2020, after Alois P. Heinz *)

Formula

a(n) ~ (-1)^n * n^n * (1 + 1/n^2 - 1/n^3 + 2/n^4 - 2/n^5 + 4/n^6 - 4/n^7 + 7/n^8 - 8/n^9 + 12/n^10), for coefficients see A002865. - Vaclav Kotesovec, Sep 19 2017
Showing 1-5 of 5 results.