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 11-20 of 21 results. Next

A341225 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^6.

Original entry on oeis.org

1, 12, 78, 370, 1437, 4848, 14719, 41148, 107610, 266296, 628941, 1427118, 3127369, 6646440, 13746081, 27744926, 54782271, 106029918, 201512970, 376630680, 693161334, 1257641676, 2251764699, 3982196910, 6961522279, 12038699766, 20607718317, 34938910360
Offset: 6

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 6):
    seq(a(n), n=6..33);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 33; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^6, {x, 0, nmax}], x] // Drop[#, 6] &

A341226 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^7.

Original entry on oeis.org

1, 14, 105, 567, 2478, 9317, 31269, 95965, 273896, 735966, 1879059, 4591342, 10797290, 24549924, 54171729, 116368308, 243991034, 500446135, 1006039762, 1985480063, 3852429483, 7358212272, 13850448185, 25718189483, 47150564517, 85417834621, 153015826880
Offset: 7

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 7):
    seq(a(n), n=7..33);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 33; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^7, {x, 0, nmax}], x] // Drop[#, 7] &

A341227 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^8.

Original entry on oeis.org

1, 16, 136, 824, 4004, 16608, 61076, 204200, 631714, 1831752, 5027312, 13159104, 33049090, 80030808, 187613348, 427201176, 947520103, 2051989360, 4347996772, 9030416704, 18412343832, 36905322248, 72807201940, 141525042736, 271321432489, 513454659312
Offset: 8

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 8):
    seq(a(n), n=8..33);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 33; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^8, {x, 0, nmax}], x] // Drop[#, 8] &

A341228 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^9.

Original entry on oeis.org

1, 18, 171, 1149, 6147, 27891, 111567, 403722, 1345896, 4189334, 12300174, 34337403, 91721385, 235645425, 584759880, 1406588073, 3289489002, 7498465029, 16697615817, 36391839264, 77758115283, 163123713621, 336420277812, 682877289213, 1365674365197, 2693384989056
Offset: 9

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 9):
    seq(a(n), n=9..34);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 34; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^9, {x, 0, nmax}], x] // Drop[#, 9] &

A358912 Number of finite sequences of integer partitions with total sum n and all distinct lengths.

Original entry on oeis.org

1, 1, 2, 5, 11, 23, 49, 103, 214, 434, 874, 1738, 3443, 6765, 13193, 25512, 48957, 93267, 176595, 332550, 622957, 1161230, 2153710, 3974809, 7299707, 13343290, 24280924, 43999100, 79412942, 142792535, 255826836, 456735456, 812627069, 1440971069, 2546729830
Offset: 0

Views

Author

Gus Wiseman, Dec 07 2022

Keywords

Examples

			The a(1) = 1 through a(4) = 11 sequences:
  (1)  (2)   (3)      (4)
       (11)  (21)     (22)
             (111)    (31)
             (1)(11)  (211)
             (11)(1)  (1111)
                      (11)(2)
                      (1)(21)
                      (2)(11)
                      (21)(1)
                      (1)(111)
                      (111)(1)
		

Crossrefs

The case of set partitions is A007837.
This is the case of A055887 with all distinct lengths.
For distinct sums instead of lengths we have A336342.
The case of twice-partitions is A358830.
The unordered version is A358836.
The version for constant instead of distinct lengths is A358905.
A000041 counts integer partitions, strict A000009.
A063834 counts twice-partitions.
A141199 counts sequences of partitions with weakly decreasing lengths.

Programs

  • Mathematica
    ptnseq[n_]:=Join@@Table[Tuples[IntegerPartitions/@comp],{comp,Join@@Permutations/@IntegerPartitions[n]}];
    Table[Length[Select[ptnseq[n],UnsameQ@@Length/@#&]],{n,0,10}]
  • PARI
    P(n,y) = {1/prod(k=1, n, 1 - y*x^k + O(x*x^n))}
    seq(n) = {my(g=P(n,y)); [subst(serlaplace(p), y, 1) | p<-Vec(prod(k=1, n, 1 + y*polcoef(g, k, y) + O(x*x^n)))]} \\ Andrew Howroyd, Dec 30 2022

Extensions

Terms a(16) and beyond from Andrew Howroyd, Dec 30 2022

A326346 Total number of partitions in the partitions of compositions of n.

Original entry on oeis.org

0, 1, 4, 14, 47, 151, 474, 1457, 4414, 13210, 39155, 115120, 336183, 976070, 2819785, 8110657, 23239662, 66362960, 188930728, 536407146, 1519205230, 4293061640, 12106883585, 34079016842, 95762829405, 268670620736, 752676269695, 2105751165046, 5883798478398
Offset: 0

Views

Author

Alois P. Heinz, Sep 11 2019

Keywords

Examples

			a(3) = 14 = 1+1+1+2+2+2+2+3 counts the partitions in 3, 21, 111, 2|1, 11|1, 1|2, 1|11, 1|1|1.
		

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, [1, 0], (p-> p+
          [0, p[1]])(add(combinat[numbpart](j)*b(n-j), j=1..n)))
        end:
    a:= n-> b(n)[2]:
    seq(a(n), n=0..32);
  • Mathematica
    b[n_] := b[n] = If[n==0, {1, 0}, Function[p, p + {0, p[[1]]}][Sum[ PartitionsP[j] b[n-j], {j, 1, n}]]];
    a[n_] := b[n][[2]];
    a /@ Range[0, 32] (* Jean-François Alcover, Dec 05 2020, after Alois P. Heinz *)

Formula

a(n) = Sum_{k=1..n} k * A060642(n,k).
a(n) ~ c * d^n * n, where d = A246828 = 2.69832910647421123126399866618837633... and c = 0.171490233695958246364725709205670983251448838158816... - Vaclav Kotesovec, Sep 14 2019

A340987 Number of colored integer partitions of 2n such that all colors from an n-set are used.

Original entry on oeis.org

1, 2, 10, 59, 362, 2287, 14719, 95965, 631714, 4189334, 27946335, 187319827, 1260570515, 8511460908, 57634550179, 391232510284, 2661483301282, 18140003082945, 123846214549072, 846801764644618, 5797865791444367, 39745254613927264, 272762265331208465
Offset: 0

Views

Author

Alois P. Heinz, Feb 01 2021

Keywords

Examples

			a(1) = 2: 2a, 1a1a.
a(2) = 10: 3a1b, 3b1a, 2a2b, 2a1b1b, 2b1a1a, 2a1a1b, 2b1a1b, 1a1b1b1b, 1a1a1b1b, 1a1a1a1b.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, combinat[numbpart](n+1),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..25);
  • Mathematica
    b[n_, k_] := b[n, k] = If[k<2, PartitionsP[n+1], With[{q = Quotient[k, 2]}, Sum[b[j, q] b[n-j, k-q], {j, 0, n}]]];
    a[n_] := b[n, n];
    a /@ Range[0, 25] (* Jean-François Alcover, Feb 04 2021, after Alois P. Heinz *)
    Table[SeriesCoefficient[(-1 + 1/QPochhammer[Sqrt[x]])^n, {x, 0, n}], {n, 0, 25}] (* Vaclav Kotesovec, Jan 15 2024 *)
    (* Calculation of constant d: *) 1/r/.FindRoot[{1 + s == 1/QPochhammer[Sqrt[r*s]], 1/(1 + s) + Sqrt[r]*(1 + s)*Derivative[0, 1][QPochhammer][Sqrt[r*s], Sqrt[r*s]] / (2*Sqrt[s]) == (Log[1 - Sqrt[r*s]] + QPolyGamma[0, 1, Sqrt[r*s]]) / (s*Log[r*s])}, {r, 1/7}, {s, 1}, WorkingPrecision -> 120] (* Vaclav Kotesovec, Jan 15 2024 *)

Formula

a(n) = [x^(2n)] (-1 + Product_{j>0} 1/(1-x^j))^n.
a(n) = A060642(2*n,n).
a(n) = Sum_{i=0..n} (-1)^i * C(n,i) * A144064(2n,n-i).
a(n) ~ c * d^n / sqrt(n), where d = 7.0224714601856191637116674203375767768930294104680988528373522936595686998... and c = 0.306577097117652483059452115503859901867921865482563952948772592499558... - Vaclav Kotesovec, Feb 14 2021

A119442 Triangle read by rows: row n lists number of unordered partitions of n into k parts which are partition numbers (members of A000041).

Original entry on oeis.org

1, 2, 1, 3, 2, 1, 5, 7, 2, 1, 7, 11, 7, 2, 1, 11, 26, 19, 7, 2, 1, 15, 40, 38, 19, 7, 2, 1, 22, 83, 78, 54, 19, 7, 2, 1, 30, 120, 168, 102, 54, 19, 7, 2, 1, 42, 223, 301, 244, 134, 54, 19, 7, 2, 1, 56, 320, 557, 471, 292, 134, 54, 19, 7, 2, 1, 77, 566, 1035, 1000, 623, 356, 134, 54
Offset: 0

Views

Author

Alford Arnold, May 19 2006

Keywords

Comments

A060642 describes the ordered case.
Number of twice-partitions of n of length k. A twice-partition of n is a choice of a partition of each part in a partition of n. - Gus Wiseman, Mar 23 2018

Examples

			Triangle begins:
   1
   2   1
   3   2   1
   5   7   2   1
   7  11   7   2   1
  11  26  19   7   2   1
  15  40  38  19   7   2   1
  22  83  78  54  19   7   2   1
  30 120 168 102  54  19   7   2   1
  42 223 301 244 134  54  19   7   2   1
  56 320 557 471 292 134  54  19   7   2   1
The T(5,3) = 7 twice-partitions: (3)(1)(1), (21)(1)(1), (111)(1)(1), (2)(2)(1), (2)(11)(1), (11)(2)(1), (11)(11)(1). - _Gus Wiseman_, Mar 23 2018
		

Crossrefs

Programs

  • Mathematica
    nn=12;
    ser=Product[1/(1-PartitionsP[n]x^n y),{n,nn}];
    Table[SeriesCoefficient[ser,{x,0,n},{y,0,k}],{n,nn},{k,n}] (* Gus Wiseman, Mar 23 2018 *)

Formula

G.f.: 1/Product_{k>0} (1-y*A000041(k)*x^k). - Vladeta Jovovic, May 21 2006

Extensions

More terms and better definition from Vladeta Jovovic, May 21 2006

A327549 Number T(n,k) of compositions of partitions of n with exactly k compositions; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 2, 1, 0, 4, 2, 1, 0, 8, 8, 2, 1, 0, 16, 16, 8, 2, 1, 0, 32, 48, 24, 8, 2, 1, 0, 64, 96, 64, 24, 8, 2, 1, 0, 128, 256, 160, 80, 24, 8, 2, 1, 0, 256, 512, 448, 192, 80, 24, 8, 2, 1, 0, 512, 1280, 1024, 576, 224, 80, 24, 8, 2, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 16 2019

Keywords

Examples

			T(3,1) = 4: 3, 21, 12, 111.
T(3,2) = 2: 2|1, 11|1.
T(3,3) = 1: 1|1|1.
Triangle T(n,k) begins:
  1;
  0,   1;
  0,   2,    1;
  0,   4,    2,    1;
  0,   8,    8,    2,   1;
  0,  16,   16,    8,   2,   1;
  0,  32,   48,   24,   8,   2,  1;
  0,  64,   96,   64,  24,   8,  2,  1;
  0, 128,  256,  160,  80,  24,  8,  2, 1;
  0, 256,  512,  448, 192,  80, 24,  8, 2, 1;
  0, 512, 1280, 1024, 576, 224, 80, 24, 8, 2, 1;
  ...
		

Crossrefs

Columns k=0-2 give: A000007, A011782 (for n>0), A134353(n-2) (for n>1).
Row sums give A075900.
T(2n,n) gives A327550.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+expand(2^(i-1)*x*b(n-i, min(n-i, i)))))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(b(n$2)):
    seq(T(n), n=0..12);
  • Mathematica
    b[n_, i_] := b[n, i] = If[n==0, 1, If[i<1, 0, b[n, i-1] + 2^(i-1) x b[n-i, Min[n-i, i]]]];
    T[n_] := CoefficientList[b[n, n], x];
    T /@ Range[0, 12] // Flatten (* Jean-François Alcover, Dec 17 2020, after Alois P. Heinz *)

Formula

Sum_{k=1..n} k * T(n,k) = A327548(n).

A341236 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^10.

Original entry on oeis.org

1, 20, 210, 1550, 9055, 44624, 192945, 751480, 2686155, 8934560, 27946335, 82884860, 234636435, 637416140, 1669127130, 4228739712, 10398140075, 24882425770, 58080468790, 132508486900, 296005537183, 648445364080, 1394961003490, 2950516502980, 6142674032345, 12599932782780
Offset: 10

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 10):
    seq(a(n), n=10..35);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 35; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^10, {x, 0, nmax}], x] // Drop[#, 10] &
Previous Showing 11-20 of 21 results. Next