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 1-10 of 12 results. Next

A292745 Number A(n,k) of partitions of n with k sorts of part 1 which are introduced in ascending order; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 3, 2, 1, 1, 3, 6, 5, 2, 1, 1, 3, 7, 13, 7, 4, 1, 1, 3, 7, 19, 26, 11, 4, 1, 1, 3, 7, 20, 52, 54, 15, 7, 1, 1, 3, 7, 20, 62, 151, 108, 22, 8, 1, 1, 3, 7, 20, 63, 217, 442, 219, 30, 12, 1, 1, 3, 7, 20, 63, 232, 803, 1314, 439, 42, 14
Offset: 0

Views

Author

Alois P. Heinz, Sep 22 2017

Keywords

Examples

			A(3,2) = 6: 3, 21a, 1a1a1a, 1a1a1b, 1a1b1a, 1a1b1b.
Square array A(n,k) begins:
  1,  1,   1,    1,    1,    1,    1,    1,    1, ...
  0,  1,   1,    1,    1,    1,    1,    1,    1, ...
  1,  2,   3,    3,    3,    3,    3,    3,    3, ...
  1,  3,   6,    7,    7,    7,    7,    7,    7, ...
  2,  5,  13,   19,   20,   20,   20,   20,   20, ...
  2,  7,  26,   52,   62,   63,   63,   63,   63, ...
  4, 11,  54,  151,  217,  232,  233,  233,  233, ...
  4, 15, 108,  442,  803,  944,  965,  966,  966, ...
  7, 22, 219, 1314, 3092, 4158, 4425, 4453, 4454, ...
		

Crossrefs

Main diagonal gives A292503.

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, k)-> b(n$2, k):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • 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_, k_] := b[n, n, k];
    Table[A[n, d - n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, May 17 2018, translated from Maple *)

Formula

A(n,k) = Sum_{j=0..k} A292746(n,j).
A(n,k) = A(n,n) for all k >= n.

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 *)

A259401 a(n) = Sum_{k=0..n} 2^(n-k)*p(k), where p(k) is the partition function A000041.

Original entry on oeis.org

1, 3, 8, 19, 43, 93, 197, 409, 840, 1710, 3462, 6980, 14037, 28175, 56485, 113146, 226523, 453343, 907071, 1814632, 3629891, 7260574, 14522150, 29045555, 58092685, 116187328, 232377092, 464757194, 929518106, 1859040777, 3718087158, 7436181158, 14872370665
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 26 2015

Keywords

Comments

In general, Sum_{k=0..n} (m^(n-k) * p(k)) ~ m^n / QPochhammer[1/m, 1/m], for m > 1.

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<0, 0,
          2*a(n-1)+combinat[numbpart](n))
        end:
    seq(a(n), n=0..32);  # Alois P. Heinz, Dec 03 2019
  • Mathematica
    Table[Sum[2^(n-k)*PartitionsP[k],{k,0,n}],{n,0,50}]
  • PARI
    a(n) = sum(k=0, n, 2^(n-k)*numbpart(k)); \\ Michel Marcus, Dec 03 2019

Formula

a(n) ~ c * 2^n, where c = 1/A048651 = 1/QPochhammer[1/2, 1/2] = 3.462746619455...
G.f.: (1/(1 - 2*x)) * Product_{k>=1} 1/(1 - x^k). - Ilya Gutkovskiy, Dec 03 2019

A292747 Number of partitions of 2n with exactly n kinds of 1's which are introduced in ascending order.

Original entry on oeis.org

1, 1, 8, 97, 1778, 43747, 1349703, 50033463, 2164920950, 107074391802, 5957871478583, 368330684797595, 25046735249606820, 1857906353180702199, 149289720057575358424, 12917953683720554797237, 1197556745092101849164899, 118414507831659267311128558
Offset: 0

Views

Author

Alois P. Heinz, Sep 22 2017

Keywords

Examples

			a(2) = 8: 21a1b, 1a1a1a1b, 1a1a1b1a, 1a1a1b1b, 1a1b1a1a, 1a1b1a1b, 1a1b1b1a, 1a1b1b1b  (the two kinds of 1's are denoted by 1a and 1b).
		

Crossrefs

Cf. 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(2*n$2, n)-b(2*n$2, n-1):
    seq(a(n), n=0..20);
  • 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[2n, 2n, n] - b[2n, 2n, n-1];
    a /@ Range[0, 20] (* Jean-François Alcover, Dec 12 2020, after Alois P. Heinz *)

Formula

a(n) = A292746(2n,n).
a(n) ~ 2^(2*n) * n^(n-1/2) / (sqrt(2*Pi*(1-c)) * exp(n) * c^n * (2-c)^n), where c = -LambertW(-2*exp(-2)) = -A226775 = 0.40637573995995990767695812412483975821... - Vaclav Kotesovec, Sep 28 2017

A320816 Number of partitions of n with exactly three sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 6, 26, 97, 334, 1095, 3482, 10855, 33405, 101925, 309237, 934691, 2818110, 8482505, 25504000, 76625146, 230101961, 690759226, 2073184749, 6221368879, 18667736528, 56010470158, 168045932624, 504166843427, 1512558622966, 4537792056226, 13613608545770
Offset: 3

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=3 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(3):
    seq(a(n), n=3..35);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i < 2, Sum[StirlingS2[n, j], {j, 0, k}], Sum[b[n - i*j, i - 1, k], {j, 0, n/i}]];
    a[n_] := With[{k = 3}, b[n, n, k] - b[n, n, k - 1]];
    a /@ Range[3, 35] (* Jean-François Alcover, Dec 16 2020, after Alois P. Heinz *)

Formula

a(n) = A320734(n) - A320733(n).

A320817 Number of partitions of n with exactly four sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 10, 66, 361, 1778, 8207, 36310, 156095, 657785, 2733065, 11241497, 45900679, 186420826, 754165809, 3042167236, 12245294090, 49211278321, 197535872510, 792216674789, 3175088068035, 12719020008668, 50932090504830, 203896407951944, 816089798651203
Offset: 4

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=4 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(4):
    seq(a(n), n=4..35);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i < 2, Sum[StirlingS2[n, j], {j, 0, k}], Sum[b[n - i*j, i - 1, k], {j, 0, n/i}]];
    a[n_] := With[{k = 4}, b[n, n, k] - b[n, n, k-1]];
    a /@ Range[4, 35] (* Jean-François Alcover, Dec 17 2020, after Alois P. Heinz *)

Formula

a(n) = A320735(n) - A320734(n).

A320818 Number of partitions of n with exactly five sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 15, 141, 1066, 7108, 43747, 255045, 1431320, 7814385, 41804990, 220266447, 1147232914, 5922585396, 30367092789, 154877631181, 786633449995, 3982378528296, 20109428513990, 101339359244739, 509871884291730, 2562078441467318, 12861324297841420
Offset: 5

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=5 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(5):
    seq(a(n), n=5..35);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i < 2, Sum[StirlingS2[n, j], {j, 0, k}], Sum[b[n - i*j, i - 1, k], {j, 0, n/i}]];
    a[n_] := With[{k = 5}, b[n, n, k] - b[n, n, k - 1]];
    a /@ Range[5, 35] (* Jean-François Alcover, Dec 17 2020, after Alois P. Heinz *)

Formula

a(n) = A320736(n) - A320735(n).

A320819 Number of partitions of n with exactly six sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 21, 267, 2668, 23116, 182443, 1349703, 9529538, 64991613, 431754668, 2810794455, 18011999644, 113994583260, 714334592349, 4440885185275, 27431944561645, 168574045898166, 1031553703902986, 6290661582662655, 38253841380267660, 232085126723073278
Offset: 6

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=6 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(6):
    seq(a(n), n=6..35);

Formula

a(n) = A320737(n) - A320736(n).

A320820 Number of partitions of n with exactly seven sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 28, 463, 5909, 64479, 633796, 5786275, 50033463, 415225854, 3338335646, 26179143977, 201266007483, 1522856635641, 11374331041836, 84061202478127, 615860361908534, 4479596579257904, 32388729758708314, 233011769893620853, 1669336230635613631
Offset: 7

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=7 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(7):
    seq(a(n), n=7..35);

Formula

a(n) = A320738(n) - A320737(n).

A320821 Number of partitions of n with exactly eight sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 36, 751, 11917, 159815, 1912316, 21084803, 218711887, 2164920950, 20657703246, 191440769945, 1732792167043, 15385193971985, 134455882817716, 1159708265019855, 9893526482067374, 83627808435796896, 701411197245083482, 5844301347854288709, 48423747013469923303
Offset: 8

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=8 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(8):
    seq(a(n), n=8..35);

Formula

a(n) = A320739(n) - A320738(n).
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