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 15 results. Next

A246935 Number A(n,k) of partitions of n into k sorts of parts; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 6, 3, 0, 1, 4, 12, 14, 5, 0, 1, 5, 20, 39, 34, 7, 0, 1, 6, 30, 84, 129, 74, 11, 0, 1, 7, 42, 155, 356, 399, 166, 15, 0, 1, 8, 56, 258, 805, 1444, 1245, 350, 22, 0, 1, 9, 72, 399, 1590, 4055, 5876, 3783, 746, 30, 0
Offset: 0

Views

Author

Alois P. Heinz, Sep 08 2014

Keywords

Comments

In general, column k > 1 is asymptotic to c * k^n, where c = Product_{j>=1} 1/(1-1/k^j) = 1/QPochhammer[1/k,1/k]. - Vaclav Kotesovec, Mar 19 2015
When k is a prime power greater than 1, A(n,k) is the number of conjugacy classes of n X n matrices over a field of size k. - Geoffrey Critzer, Nov 11 2022

Examples

			A(2,2) = 6: [2a], [2b], [1a,1a], [1a,1b], [1b,1a], [1b,1b].
Square array A(n,k) begins:
  1,  1,   1,    1,     1,      1,      1,      1, ...
  0,  1,   2,    3,     4,      5,      6,      7, ...
  0,  2,   6,   12,    20,     30,     42,     56, ...
  0,  3,  14,   39,    84,    155,    258,    399, ...
  0,  5,  34,  129,   356,    805,   1590,   2849, ...
  0,  7,  74,  399,  1444,   4055,   9582,  19999, ...
  0, 11, 166, 1245,  5876,  20455,  57786, 140441, ...
  0, 15, 350, 3783, 23604, 102455, 347010, 983535, ...
		

Crossrefs

Rows n=0-4 give: A000012, A001477, A002378, A027444, A186636.
Main diagonal gives A124577.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k))))
        end:
    A:= (n, k)-> b(n$2, k):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i<1, 0, b[n, i-1, k] + If[i>n, 0, k*b[n-i, i, k]]]]; A[n_, k_] := b[n, n, k];  Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Feb 03 2015, after Alois P. Heinz *)

Formula

G.f. of column k: Product_{i>=1} 1/(1-k*x^i).
T(n,k) = Sum_{i=0..k} C(k,i) * A255970(n,i).

A291698 a(n) = [x^n] Product_{k>=1} (1 + n*x^k).

Original entry on oeis.org

1, 1, 2, 12, 20, 55, 294, 497, 1224, 2520, 14410, 21912, 54300, 104286, 220710, 1105215, 1697552, 3839382, 7356762, 14873580, 26275620, 132112596, 188666126, 423247104, 772560600, 1535398150, 2632049290, 4975242048, 21273166572, 30649985160, 64824339630, 116604788800, 223181224992
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 30 2017

Keywords

Comments

The number of partitions of n into distinct parts where each part can be colored in n different ways. For example, there are 4 partitions of 6 into distinct parts, namely 6, 5 + 1, 4 + 2 and 3 + 2 + 1; allowing for the colorings gives a(6) = 6 + 6*6 + 6*6 + 6*6*6 = 294. - Peter Bala, Aug 31 2017

Crossrefs

Main diagonal of A286957.

Programs

  • Maple
    seq(coeff(mul(1+n*x^k,k=1..n),x,n),n=0..50); # Robert Israel, Aug 30 2017
  • Mathematica
    Table[SeriesCoefficient[Product[1 + n x^k, {k, 1, n}], {x, 0, n}], {n, 0, 32}]
    Table[SeriesCoefficient[QPochhammer[-n, x]/(1 + n), {x, 0, n}], {n, 0, 32}]

Formula

a(n) = A286957(n,n).
a(n) == 0 (mod n); a(n) == n (mod n^2). - Peter Bala, Aug 31 2017
Conjecture: a(n) ~ exp(sqrt(2*(log(n)^2 + Pi^2/3)*n)) * (log(n)^2 + Pi^2/3)^(1/4) / (sqrt(Pi) * (2*n)^(5/4)). - Vaclav Kotesovec, Sep 15 2017

A103923 Triangle of partitions of n with parts of sizes 1,2,...,m, each of two different kinds, m>=1.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 3, 4, 2, 1, 5, 7, 5, 2, 1, 7, 12, 9, 5, 2, 1, 11, 19, 17, 10, 5, 2, 1, 15, 30, 28, 19, 10, 5, 2, 1, 22, 45, 47, 33, 20, 10, 5, 2, 1, 30, 67, 73, 57, 35, 20, 10, 5, 2, 1, 42, 97, 114, 92, 62, 36, 20, 10, 5, 2, 1, 56, 139, 170, 147, 102, 64, 36, 20, 10, 5, 2, 1, 77, 195
Offset: 0

Views

Author

Wolfdieter Lang, Mar 24 2005

Keywords

Comments

The corresponding Fine-Riordan triangle is A008951.
This is the array p_2(n,m) of Gupta et al. written as a triangle. p_2(n,m) is defined on p. x of this reference as the number of partitions of n into parts consisting of two varieties of each of the integers 1 to m and one variety of each larger integer. Therefore a(n,m) gives these numbers for the partitions of n-m.
a(n,m)= sum over partitions of n+t(m)-m of binomial(q(partition),m), with t(m):=A000217(m) and q the number of distinct parts of a given partition. m>=0.
a(n,m)= number of partitions of 2*n-m with exactly m odd parts.
a(n,m)= sum over partitions of n+t(m)-m of product(k[j],j=1..m), with t(m):=A000217(m) and k[j]=number of parts of size j (exponent of j in a given partition of n), if m>=1. If m=0 then a(n,0)=p(n):=A000041(n) (number of partitions of n). 0 is counted as a part for n=0 and only for this n.

Examples

			Triangle starts:
[1];
[1,1];
[2,2,1];
[3,4,2,1];
[5,7,5,2,1];
...
a(4,2)=5 from the partitions of 4-2=2 with two varieties of parts 1 and of 2, namely (2),(2'),(1^2),(1'^2) and (1,1').
a(4,2)=5 from the partitions of 4+t(2)-2=5 which have products of the exponents of parts 1 and 2: 0*0,1*0,0*1,2*1,1*2,5*0 and sum to 4.
a(4,2)=5 from the partitions of 4+t(2)-2=5 which have number of distinct parts (q values) 1,2,2,2,2,2,1. The corresponding binomial(q,2) values are 0,1,1,1,1,0 and sum to 4.
a(4,2)=5 from the partitions of 2*4-2=6 with exactly two odd parts, namely (1,5), (3^2), (1^2,4), (1,2,3) and (1^2,2^2), which are 5 in number.
		

References

  • H. Gupta et al., Tables of Partitions. Royal Society Mathematical Tables, Vol. 4, Cambridge Univ. Press, 1958 (reprinted 1962), pp. 90-121.
  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 199.

Crossrefs

The column sequences (without leading 0's) are, for m=0..10: A000041, A000070, A000097, A000098, A000710, A103924-A103929.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n=0, 1, add(add(d*
          `if`(d<=k, 2, 1), d=divisors(j)) *b(n-j, k), j=1..n)/n)
        end:
    A:= (n, k)-> b(n, k) -`if`(k=0, 0, b(n, k-1)):
    seq(seq(A(n, k), k=0..n), n=0..14);  # Alois P. Heinz, Sep 14 2014
  • Mathematica
    a[n_, 0] := a[n, 0] = PartitionsP[n]; a[n_, m_] /; n= m >= 0 := a[n, m] = a[n-1, m-1] + a[n-m, m]; Table[a[n, m], {n, 0, 14}, {m, 0, n}] // Flatten (* Jean-François Alcover, Dec 09 2014 *)
    Flatten@Table[Length@IntegerPartitions[n-m, All, Range@n~Join~Range@m],  {n, 0, 12}, {m, 0, n}] (* Robert Price, Jul 29 2020 *)

Formula

a(n, m) = a(n-1, m-1) + a(n-m, m), n>=m>=0, with a(n, 0)= A000041(n) (partition numbers), a(n, m)=0 if n
a(n, m) = sum(a(n-1-j*m, m-1), j=0..floor((n-m)/m)), m>=1, input a(n, 0)= A000041(n).
G.f. column m: product(1/(1-x^j), j=1..m)*P(x), with P(x)= product(1/(1-x^j), j=1..infty), the o.g.f. for the partition numbers A000041.
G.f. column m>=1: (product(1/(1-x^k), k=1..m)^2)*product(1/(1-x^j), j=(m+1)..infty). For m=0 put the first product equal to 1.

A209664 T(n,k) = count of degree k monomials in the power sum symmetric polynomials p(mu,k) summed over all partitions mu of n.

Original entry on oeis.org

1, 2, 6, 3, 14, 39, 5, 34, 129, 356, 7, 74, 399, 1444, 4055, 11, 166, 1245, 5876, 20455, 57786, 15, 350, 3783, 23604, 102455, 347010, 983535, 22, 746, 11514, 94852, 513230, 2083902, 6887986, 19520264, 30, 1546, 34734, 379908, 2567230, 12505470, 48219486, 156167944, 441967518
Offset: 1

Author

Wouter Meeussen, Mar 11 2012

Keywords

Examples

			Table starts as:
:  1;
:  2,   6;
:  3,  14,   39;
:  5,  34,  129,  356;
:  7,  74,  399, 1444,  4055;
: 11, 166, 1245, 5876, 20455, 57786;
		

Crossrefs

Main diagonal is A124577; row sums are A209665.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k))))
        end:
    T:= (n, k)-> b(n$2, k):
    seq(seq(T(n, k), k=1..n), n=1..10);  # Alois P. Heinz, Nov 24 2016
  • Mathematica
    p[n_Integer, v_] := Sum[Subscript[x, j]^n, {j, v}]; p[par_?PartitionQ, v_] := Times @@ (p[#, v] & /@ par); Table[Tr[(p[#, k] & /@ Partitions[l]) /. Subscript[x, _] -> 1], {l, 11}, {k, l}]

A298985 a(n) = [x^n] Product_{k>=1} 1/(1 - n*x^k)^k.

Original entry on oeis.org

1, 1, 8, 54, 496, 5400, 73728, 1204322, 23167808, 512093178, 12781430600, 355128859129, 10863077554224, 362572265689777, 13107541496092960, 510105773344747725, 21258690342206888192, 944467894258279964254, 44555341678790400325512, 2224158766859058600584834, 117123916650423288611260400
Offset: 0

Author

Ilya Gutkovskiy, Jan 31 2018

Keywords

Programs

  • Maple
    b:= proc(n, i, k) option remember;   `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(i+j-1, j)*b(n-i*j, i-1, k)*k^j, j=0..n/i)))
        end:
    a:= n-> b(n$3):
    seq(a(n), n=0..30);  # Alois P. Heinz, Sep 23 2018
  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - n x^k)^k, {k, 1, n}], {x, 0, n}], {n, 0, 20}]

Formula

a(n) ~ n^n. - Vaclav Kotesovec, Feb 02 2018

A292132 Main diagonal of A292131.

Original entry on oeis.org

1, -1, -2, 6, 12, 45, -150, -203, -840, -1872, 6390, 8580, 30084, 69108, 165802, -494565, -514320, -1997296, -4202298, -10175526, -18908420, 49930440, 54032770, 190735688, 405256872, 948210600, 1751280726, 3624555168, -7676955468, -6724059944, -26741354430
Offset: 0

Author

Seiichi Manyama, Sep 09 2017

Keywords

Crossrefs

Programs

  • PARI
    {a(n) = polcoeff(prod(k=1, n, 1-n*x^k+x*O(x^n)), n)}

Formula

a(n) = [x^n] Product_{k=1..n} (1 - n*x^k).

A292134 Main diagonal of A292133.

Original entry on oeis.org

1, -1, 2, -21, 220, -2705, 40926, -733537, 15124216, -352606050, 9174382490, -263533561852, 8283376452948, -282795708021411, 10420847619031710, -412243715452039440, 17425722339237083120, -783844576340696848341, 37384875796116662077194
Offset: 0

Author

Seiichi Manyama, Sep 09 2017

Keywords

Crossrefs

Programs

  • PARI
    {a(n) = polcoeff(1/prod(k=1, n, 1+n*x^k+x*O(x^n)), n)}

Formula

a(n) = [x^n] Product_{k>=1} 1/(1 + n*x^k).
a(n) ~ (-1)^n * n^n * (1 - 1/n + 2/n^2 - 3/n^3 + 5/n^4 - 7/n^5 + 11/n^6 - 15/n^7 + 22/n^8 - 30/n^9 + 42/n^10 - ...), for coefficients, see A000041. - Vaclav Kotesovec, Aug 21 2018

A303175 a(n) = [x^n] Product_{k=1..n} 1/(1 - (n - k + 1)*x^k).

Original entry on oeis.org

1, 1, 5, 34, 322, 3803, 55297, 953815, 19086057, 434477488, 11086102633, 313318606066, 9714265351819, 327788649292844, 11957321196905337, 468872400449456885, 19666225828334583690, 878560858388253803180, 41645712575272737701666, 2087686693048676581394052
Offset: 0

Author

Ilya Gutkovskiy, Apr 19 2018

Keywords

Examples

			a(0) = 1;
a(1) = [x^1] 1/(1 - x) = 1;
a(2) = [x^2] 1/((1 - 2*x)*(1 - x^2)) = 5;
a(3) = [x^3] 1/((1 - 3*x)*(1 - 2*x^2)*(1 - x^3)) = 34;
a(4) = [x^4] 1/((1 - 4*x)*(1 - 3*x^2)*(1 - 2*x^3)*(1 - x^4)) = 322;
a(5) = [x^5] 1/((1 - 5*x)*(1 - 4*x^2)*(1 - 3*x^3)*(1 - 2*x^4)*(1 - x^5)) = 3803, etc.
...
The table of coefficients of x^k in expansion of Product_{k=1..n} 1/(1 - (n - k + 1)*x^k) begins:
n = 0: (1), 0,   0,    0,    0,     0,  ...
n = 1:  1, (1),  1,    1,    1,     1,  ...
n = 2:  1,  2,  (5),  10,   21,    42,  ...
n = 3:  1,  3,  11,  (34), 106,   320,  ...
n = 4:  1,  4,  19,   78, (322), 1294,  ...
n = 5:  1,  5,  29,  148,  758, (3803), ...
		

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - (n - k + 1) x^k), {k, 1, n}], {x, 0, n}], {n, 0, 19}]

Formula

a(n) ~ n^n * (1 + 1/n + 1/n^2 - 1/n^3 - 3/n^4 - 8/n^5 - 7/n^6 - 13/n^7 + 2/n^8 - 3/n^9 + 31/n^10 + 21/n^11 + 81/n^12 + 2/n^13 + 152/n^14 - 114/n^15 + 173/n^16 - 341/n^17 + 260/n^18 - 936/n^19 + 861/n^20 - 2187/n^21 + 2630/n^22 - 4551/n^23 + 6211/n^24 - 8866/n^25 + 14889/n^26 - 22374/n^27 + 38490/n^28 - 55911/n^29 + 87688/n^30 - ...). - Vaclav Kotesovec, Aug 21 2018

A338697 a(n) = [x^n] Product_{k>=1} 1 / (1 - n^(k-1)*x^k).

Original entry on oeis.org

1, 1, 3, 13, 101, 931, 12391, 178809, 3331721, 66288142, 1589753211, 40104031166, 1183380156013, 36187564837217, 1262524447510383, 45533370885563716, 1834219414937219601, 76016894083755947753, 3479900167920331954531, 162982921698852088968886, 8341707623665223127224821
Offset: 0

Author

Ilya Gutkovskiy, Apr 24 2021

Keywords

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - n^(k - 1) x^k), {k, 1, n}], {x, 0, n}], {n, 0, 20}]
    Join[{1}, Table[Sum[Length[IntegerPartitions[n, {k}]] n^(n - k), {k, 0, n}], {n, 1, 20}]]
    Join[{1}, Table[SeriesCoefficient[x + (n-1)/(n*QPochhammer[1/n, n*x]), {x, 0, n}], {n, 1, 20}]] (* Vaclav Kotesovec, May 09 2021 *)

Formula

a(n) = Sum_{k=0..n} p(n,k) * n^(n-k), where p(n,k) is the number of partitions of n into k parts.
a(n) ~ c * n^(n-1), where c = BesselI(1,2) = A096789 = 1.590636854637329... - Vaclav Kotesovec, May 09 2021

A292417 a(n) = [x^n] Product_{k>=1} 1/(1 - n^2*x^k).

Original entry on oeis.org

1, 1, 20, 819, 70160, 10188775, 2240751636, 692647082799, 286013768613952, 151994274055319070, 101020305070908050100, 82086758986568812837856, 80056656965795630400382608, 92282612223268812357487227077, 124113156850218393012451734737460
Offset: 0

Author

Vaclav Kotesovec, Sep 16 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; Table[SeriesCoefficient[Product[1/(1-n^2*x^k), {k, 1, n}], {x, 0, n}], {n, 0, nmax}]
  • PARI
    {a(n)= polcoef(prod(k=1, n, 1/(1-n^2*x^k +x*O(x^n))), n)};
    for(n=0,20, print1(a(n), ", ")) \\ G. C. Greubel, Feb 02 2019

Formula

a(n) ~ n^(2*n) * (1 + 1/n^2 + 2/n^4 + 3/n^6 + 5/n^8 + 7/n^10), for coefficients see A000041.
Showing 1-10 of 15 results. Next