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 10 results.

A007716 Number of polynomial symmetric functions of matrix of order n under separate row and column permutations.

Original entry on oeis.org

1, 1, 4, 10, 33, 91, 298, 910, 3017, 9945, 34207, 119369, 429250, 1574224, 5916148, 22699830, 89003059, 356058540, 1453080087, 6044132794, 25612598436, 110503627621, 485161348047, 2166488899642, 9835209912767, 45370059225318, 212582817739535, 1011306624512711
Offset: 0

Views

Author

Keywords

Comments

Also, the number of nonnegative integer n X n matrices with sum of elements equal to n, under row and column permutations (cf. A120733).
This is a two-dimensional generalization of the partition function (A000041), which equals the number of length n vectors of nonnegative integers with sum n, equivalent under permutations. - Franklin T. Adams-Watters, Sep 19 2011
Also number of non-isomorphic multiset partitions of weight n. - Gus Wiseman, Sep 19 2011

Examples

			The 10 non-isomorphic multiset partitions of weight 3 are {{1, 1, 1}}, {{1, 1, 2}}, {{1, 2, 3}}, {{1}, {1, 1}}, {{1}, {1, 2}}, {{1}, {2, 2}}, {{1}, {2, 3}}, {{1}, {1}, {1}}, {{1}, {1}, {2}}, {{1}, {2}, {3}}.
		

Crossrefs

Programs

  • Mathematica
    permcount[v_] := Module[{m = 1, s = 0, k = 0, t}, For[i = 1, i <= Length[v], i++, t = v[[i]]; k = If[i>1 && t == v[[i-1]], k+1, 1]; m *= t*k; s += t]; s!/m];
    c[p_, q_, k_] := SeriesCoefficient[1/Product[(1-x^LCM[p[[i]], q[[j]]])^GCD[ p[[i]], q[[j]]], {j, 1, Length[q]}, {i, 1, Length[p]}], {x, 0, k}];
    M[m_, n_, k_] := Module[{s=0}, Do[Do[s += permcount[p]*permcount[q]*c[p, q, k], {q, IntegerPartitions[n]}], {p, IntegerPartitions[m]}]; s/(m!*n!)];
    a[n_] := a[n] = M[n, n, n];
    Table[Print[n, " ", a[n]]; a[n], {n, 0, 18}] (* Jean-François Alcover, May 03 2019, after Andrew Howroyd *)
  • PARI
    \\ See A318795
    a(n) = M(n,n,n); \\ Andrew Howroyd, Sep 03 2018
    
  • PARI
    EulerT(v)={Vec(exp(x*Ser(dirmul(v,vector(#v,n,1/n))))-1, -#v)}
    permcount(v) = {my(m=1, s=0, k=0, t); for(i=1, #v, t=v[i]; k=if(i>1&&t==v[i-1], k+1, 1); m*=t*k; s+=t); s!/m}
    K(q, t, k)={EulerT(Vec(sum(j=1, #q, gcd(t, q[j])*x^lcm(t,q[j])) + O(x*x^k), -k))}
    a(n)={my(s=0); forpart(q=n, s+=permcount(q)*polcoef(exp(x*Ser(sum(t=1, n, K(q,t,n)/t))), n)); s/n!} \\ Andrew Howroyd, Mar 29 2020

Formula

a(n) is the coefficient of x^n in the cycle index Z(S_n X S_n; x_1, x_2, ...) if we replace x_i with 1+x^i+x^(2*i)+x^(3*i)+x^(4*i)+..., where S_n X S_n is the Cartesian product of symmetric groups S_n of degree n. - Vladeta Jovovic, Mar 09 2000

Extensions

More terms from Vladeta Jovovic, Jun 28 2000
a(19)-a(25) from Max Alekseyev, Jan 22 2010
a(0)=1 prepended by Alois P. Heinz, Feb 03 2019
a(26)-a(27) from Seiichi Manyama, Nov 23 2019

A135860 a(n) = binomial(n*(n+1), n).

Original entry on oeis.org

1, 2, 15, 220, 4845, 142506, 5245786, 231917400, 11969016345, 706252528630, 46897636623981, 3461014728350400, 281014969393251275, 24894763097057357700, 2389461906843449885700, 247012484980695576597296, 27361230617617949782033713, 3233032526324680287912449550
Offset: 0

Views

Author

Paul D. Hanna, Dec 02 2007

Keywords

Crossrefs

Programs

  • Magma
    [Binomial(n*(n+1), n): n in [0..30]]; // G. C. Greubel, Feb 20 2022
    
  • Mathematica
    Table[Binomial[n^2 + n, n], {n, 0, 16}] (* Arkadiusz Wesolowski, Jul 18 2012 *)
    (* or *)
    Table[SeriesCoefficient[(1+x)^(n*(n+1)), {x, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Aug 06 2025 *)
  • PARI
    a(n)=binomial(n*(n+1),n)
    for(n=0,15,print1(a(n),", "))
    
  • PARI
    a(n)=sum(k=0,n,binomial(n,k)*binomial(n^2,k))
    for(n=0,15,print1(a(n),", "))
    
  • Sage
    [binomial(n*(n+1), n) for n in (0..30)] # G. C. Greubel, Feb 20 2022

Formula

a(n) = Sum_{k=0..n} binomial(n,k) * binomial(n^2,k). - Paul D. Hanna, Nov 18 2015
a(n) is divisible by (n+1): a(n)/(n+1) = A135861(n).
a(n) is divisible by (n^2+1): a(n)/(n^2+1) = A135862(n).
a(n) = binomial(2*A000217(n),n). - Arkadiusz Wesolowski, Jul 18 2012
a(n) = [x^n] 1/(1 - x)^(n^2+1). - Ilya Gutkovskiy, Oct 03 2017
a(n) ~ exp(n + 1/2) * n^(n - 1/2) / sqrt(2*Pi). - Vaclav Kotesovec, Feb 08 2019
a(p) == p + 1 ( mod p^4 ) for prime p >= 5 and a(2*p) == (4*p + 1)*(2*p + 1) ( mod p^4 ) for all prime p. Apply Mestrovic, equation 37. - Peter Bala, Feb 27 2020
a(n) = ((n^2 + n)!)/((n^2)! * n!). - Peter Luschny, Feb 27 2020
a(n) = [x^n] (1 + x)^(n*(n+1)). - Vaclav Kotesovec, Aug 06 2025

A214398 Triangle where the g.f. of column k is 1/(1-x)^(k^2) for k>=1, as read by rows n>=1.

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 10, 9, 1, 1, 20, 45, 16, 1, 1, 35, 165, 136, 25, 1, 1, 56, 495, 816, 325, 36, 1, 1, 84, 1287, 3876, 2925, 666, 49, 1, 1, 120, 3003, 15504, 20475, 8436, 1225, 64, 1, 1, 165, 6435, 54264, 118755, 82251, 20825, 2080, 81, 1, 1, 220, 12870, 170544
Offset: 1

Views

Author

Paul D. Hanna, Jul 15 2012

Keywords

Comments

This is also the array A(n,k) read upwards antidiagonals, where the entry in row n and column k counts the vertex-labeled digraphs with n arcs and k vertices, allowing multi-edges and multi-loops (labeled analog to A138107). The binomial formula counts the weak compositions of distributing n arcs over the k^2 positions in the adjacency matrix. - R. J. Mathar, Aug 03 2017

Examples

			Triangle begins:
1;
1, 1;
1, 4, 1;
1, 10, 9, 1;
1, 20, 45, 16, 1;
1, 35, 165, 136, 25, 1;
1, 56, 495, 816, 325, 36, 1;
1, 84, 1287, 3876, 2925, 666, 49, 1;
1, 120, 3003, 15504, 20475, 8436, 1225, 64, 1;
1, 165, 6435, 54264, 118755, 82251, 20825, 2080, 81, 1;
1, 220, 12870, 170544, 593775, 658008, 270725, 45760, 3321, 100, 1; ...
		

Crossrefs

Cf. A214400 (central terms), A178325 (row sums), A054688, A000290 (1st subdiagonal), A037270 (2nd subdiagonal).
Cf. A230049.

Programs

  • Maple
    A214398 := proc(n,k)
        binomial(k^2+n-k-1,n-k) ;
    end proc:
    seq(seq(A214398(n,k),k=1..n),n=1..10) ; # R. J. Mathar, Aug 03 2017
  • Mathematica
    nmax = 11;
    T[n_, k_] := SeriesCoefficient[1/(1-x)^(k^2), {x, 0, n-k}];
    Table[T[n, k], {n, 1, nmax}, {k, 1, n}] // Flatten
  • PARI
    T(n,k)=binomial(k^2+n-k-1,n-k)
    for(n=1,11,for(k=1,n,print1(T(n,k),", "));print(""))

Formula

T(n,k) = binomial(k^2+n-k-1, n-k).
Row sums form A178325.
Central terms form A214400.
T(n,n-2) = A037270(n-2). - R. J. Mathar, Aug 03 2017
T(n,n-3) = (n^2-6*n+11)*(n^2-6*n+10)*(n-3)^2 /6. - R. J. Mathar, Aug 03 2017

A214400 a(n) = binomial(n^2 + 3*n, n).

Original entry on oeis.org

1, 4, 45, 816, 20475, 658008, 25827165, 1198774720, 64276915527, 3911395881900, 266401260897200, 20082459351180240, 1660305826125766950, 149389005978091284720, 14533945899753270066525, 1520398315196482557890304, 170190601112537814791748255
Offset: 0

Views

Author

Paul D. Hanna, Jul 15 2012

Keywords

Comments

Equals the central terms of triangle A214398.

Crossrefs

Programs

  • Maple
    seq(binomial(n^2+3*n,n),n=0..30); # Robert Israel, Mar 04 2022
  • PARI
    a(n)=binomial(n^2+3*n, n)

Formula

a(n) = [x^n] 1/(1 - x)^((n+1)^2). - Ilya Gutkovskiy, Oct 04 2017
a(n) ~ n^(n-1/2)*exp(n+5/2)/sqrt(2*Pi). - Robert Israel, Mar 04 2022

A262030 Partition array in Abramowitz-Stegun order: Schur functions evaluated at 1.

Original entry on oeis.org

1, 3, 1, 10, 8, 1, 35, 45, 20, 15, 1, 126, 224, 175, 126, 75, 24, 1, 462, 1050, 1134, 490, 840, 896, 175, 280, 189, 35, 1, 1716, 4752, 6468, 4704, 4950, 7350, 3528, 2646, 2400, 2940, 784, 540, 392, 48, 1, 6435, 21021, 34320, 33264, 13860, 27027, 50688, 41580, 25872, 15876, 17325, 29700, 15120, 14700, 1764, 5775, 7680, 2352, 945, 720, 63, 1
Offset: 1

Views

Author

Wolfdieter Lang, Oct 15 2015

Keywords

Comments

The length of row n >= 1 of this irregular triangle is A000041(n) (partition numbers).
The Abramowitz-Stegun (A-St) order of the partitions is used.
For Schur functions (or polynomials) s^(lambda) = s(lambda(n, k);x[1], ..., x[n]) defined for the k-th partition of n (here in A-St order) see, e.g., the Macdonald reference, ch. I, 3. S-functions, p. 23, and Wikipedia reference. For the combinatorial interpretation of Schur functions see the Stanley reference.
The partition lambda(n,k) has m = m(n,k) nonincreasing parts lamda_j, j = 1..m, (the reverse of the partitions given in A-St) and n-m 0's are appended to obtain a length n partition. E.g., lambda(4, 3) = (2, 2, 0, 0) with m = 2.
The Schur function s(lambda(n, k),1,...,1) (n 1's) gives the number of semistandard Young tableaux (SSYT) for the Young (Ferrers) diagram of lambda(n, k) (forgetting about trailing 0's) with the box numbers taken out of the set {1, 2, ..., n} where the rows increase weakly and the columns increase strictly. See the Stanley reference pp. 309 and 310, and the example below.
The sum of the row numbers give A209673: 1, 4, 19, 116, 751, 5552, 43219, 366088, ...
Conjecture: The sum of the squares of row numbers give A054688: 1, 10, 165, 3876, ... = binomial(n^2+n-1, n). - Wouter Meeussen, Sep 25 2016

Examples

			The irregular triangle begins (commas separate entries for partitions of like numbers of parts in A-St order):
n\k  1     2    3    4    5   6   7    8   9 10 11
1:   1
2:   3,    1
3:  10,    8,   1
4:  35,   45   20,  15,   1
5: 126,  224  175, 126   75, 24,  1
6: 462, 1050 1134  490, 840 896 175, 280 189,35, 1
...
Row 7: 1716, 4752 6468 4704, 4950 7350 3528 2646, 2400 2940 784, 540 392, 48, 1;
Row 8: 6435, 21021 34320 33264 13860, 27027 50688 41580 25872 15876, 17325 29700 15120 14700 1764, 5775 7680 2352, 945 720, 63, 1.
...
n = 4, k = 4: lambda(4, 4) = (2,1,1,0) (m=3), SSYT (we use semicolons to separate the three rows): [1,1;2;3], [1,1;2;4], [1,1;3;4],
  [1,2;2;3], [1,2;2;4], [1,2;3;4],
  [1,3;2;3], [1,3;2;4], [1,3;3;4],
  [1,4;2;3], [1,4;2;4], [1,4;3;4],
  [2,2;3;4], [2,3;3;4], [2,4;3;4], hence a(4, 4) = 15. The three tableaux with distinct numbers are standard Young tableaux and give A117506(4, 4) = 3.
		

References

  • Macdonald, I. G., Symmetric functions and Hall polynomials, Oxford University Press, 1979.
  • Stanley, R. P., Enumerative Combinatorics, Vol. 2, Cambridge University Press 1999, sect. 7.30, pp. 308-316.

Crossrefs

Cf. A054688, A117506, A209673, A210391 (in the diagonal).

Formula

a(n, k) = Det_{i,j=1..n} x[i]^(lambda_j + n-j) / Det_{i,j=1..n} x[i]^(n-j), evaluated at x[i] = 1 for i = 1..n (after division). The denominator is the Vandermonde determinant, the numerator an alternant. See, e.g., the Macdonald reference p. 24.

A055007 Number of nonnegative integer 4 X 4 matrices with no zero rows or columns and with sum of elements equal to n.

Original entry on oeis.org

1, 0, 0, 0, 24, 528, 4648, 26224, 112666, 401424, 1246000, 3476368, 8905432, 21266208, 47875272, 102482048, 210000931, 414160240, 789572072, 1460372624, 2628456428, 4615495808, 7924479264, 13328517504, 21997272036, 35674700896, 56926058920, 89477437120
Offset: 0

Views

Author

Vladeta Jovovic, May 30 2000

Keywords

Crossrefs

Formula

Number of nonnegative integer p X q matrices with no zero rows or columns and with sum of elements equal to n is Sum_{k=0...q} (-1)^k*C(q, k)*m(p, q-k, n) where m(p, q, n)=Sum_{k=0..p} (-1)^k*C(p, k)*C((p-k)*q+n-1, n).
For p = q = 4 we get a(n) = (1/15!)*(n^15 + 120*n^14 + 6580*n^13 + 218400*n^12 + 4637542*n^11 + 61261200*n^10 + 423591740*n^9 + 164392800*n^8 - 17247717487*n^7 - 47940252360*n^6 + 346941238280*n^5 + 557885764800*n^4 - 4897231459056*n^3 + 8643549191040*n^2 - 5894285241600*n + 1307674368000).
G.f.: -(16*x^15 -192*x^14 +1040*x^13 -3356*x^12 +7200*x^11 -10952*x^10 +12544*x^9 -11712*x^8 +9664*x^7 -7088*x^6 +4224*x^5 -1844*x^4 +560*x^3 -120*x^2 +16*x -1) / (x -1)^16. - Colin Barker, Jul 11 2013

Extensions

More terms from James Sellers, May 31 2000

A386879 a(n) = [x^n] 1/(1 - x)^(n*(n-1)/2).

Original entry on oeis.org

1, 0, 1, 10, 126, 2002, 38760, 888030, 23535820, 708930508, 23930713170, 895068996640, 36749279048405, 1643385429346680, 79515468511191440, 4139207762053520646, 230672804560960311000, 13703037308872895467960, 864424422377992704918690, 57711135174726478041405270, 4065392394346039279040037520
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 06 2025

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[1/(1-x)^(n*(n-1)/2), {x, 0, n}], {n, 0, 25}]
    Join[{1}, Table[Binomial[n*(n+1)/2, n] * (n-1) / (n+1), {n, 1, 25}]]

Formula

a(n) ~ exp(n) * n^(n - 1/2) / (sqrt(Pi) * 2^(n + 1/2)).
For n > 0, a(n) = binomial(n*(n+1)/2, n) * (n-1)/(n+1).

A386880 a(n) = [x^n] 1/(1 - x)^(n*(n+1)/2).

Original entry on oeis.org

1, 1, 6, 56, 715, 11628, 230230, 5379616, 145008513, 4431613550, 151473214816, 5727160371180, 237377895350076, 10704005376506540, 521748877569771510, 27338999059076777600, 1532576541123942256285, 91527291781199227579626, 5801648509628587739612170, 389032765009190361630625600
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 06 2025

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[1/(1-x)^(n*(n+1)/2), {x, 0, n}], {n, 0, 25}]
    Join[{1}, Table[Binomial[n*(n + 3)/2, n]*(n + 1)/(n + 3), {n, 1, 25}]]

Formula

a(n) ~ exp(n+2) * n^(n - 1/2) / (sqrt(Pi) * 2^(n + 1/2)).
For n > 0, a(n) = binomial(n*(n+3)/2, n) * (n+1)/(n+3).

A055005 Number of nonnegative integer 3 X 3 matrices with no zero rows or columns and with sum of elements equal to n.

Original entry on oeis.org

1, 0, 0, 6, 63, 306, 1038, 2844, 6750, 14437, 28521, 52911, 93258, 157509, 256581, 405171, 622719, 934542, 1373158, 1979820, 2806281, 3916812, 5390496, 7323822, 9833604, 13060251, 17171415, 22366045, 28878876, 36985383, 47007231
Offset: 0

Views

Author

Vladeta Jovovic, May 30 2000

Keywords

Crossrefs

Programs

  • PARI
    a(n)=([0,1,0,0,0,0,0,0,0; 0,0,1,0,0,0,0,0,0; 0,0,0,1,0,0,0,0,0; 0,0,0,0,1,0,0,0,0; 0,0,0,0,0,1,0,0,0; 0,0,0,0,0,0,1,0,0; 0,0,0,0,0,0,0,1,0; 0,0,0,0,0,0,0,0,1; 1,-9,36,-84,126,-126,84,-36,9]^n*[1;0;0;6;63;306;1038;2844;6750])[1,1] \\ Charles R Greathouse IV, Aug 14 2023

Formula

Number of nonnegative integer p X q matrices with no zero rows or columns and with sum of elements equal to n is Sum_{k=0...q} (-1)^k*C(q, k)*m(p, q-k, n) where m(p, q, n)=Sum_{k=0..p} (-1)^k*C(p, k)*C((p-k)*q+n-1, n).
For p=q=3 we get a(n)=C(n + 8, 8) - 6*C(n + 5, 5) + 9*C(n + 3, 3) + 6*C(n + 2, 2) - 18*C(n + 1, 1) + 9=(1/8!)*(n^8 + 36*n^7 + 546*n^6 + 2520*n^5 - 7791*n^4 - 43596*n^3 + 148364*n^2 - 140400*n + 40320).
G.f.: -(9*x^8-54*x^7+132*x^6-171*x^5+135*x^4-78*x^3+36*x^2-9*x+1) / (x-1)^9. - Colin Barker, Jul 13 2013

A165984 Number of ways to put n indistinguishable balls into n^3 distinguishable boxes.

Original entry on oeis.org

1, 1, 36, 3654, 766480, 275234400, 151111164204, 117774526188844, 123672890985095232, 168324948170849366820, 288216356245328994082600, 606320062786763763996747618, 1537230010624231669678572481296, 4622745700243196227504110670860680
Offset: 0

Views

Author

Thomas Wieder, Oct 03 2009

Keywords

Comments

See A165817 for the case n indistinguishable balls into 2*n distinguishable boxes.
See A054688 for the case n indistinguishable balls into n^2 distinguishable boxes.
a(n) is the number of (weak) compositions of n into n^3 parts. - Joerg Arndt, Oct 04 2017

Examples

			For n = 2 the a(2) = 36 solutions are
[0, 0, 0, 0, 0, 0, 0, 2]
[0, 0, 0, 0, 0, 0, 1, 1]
[0, 0, 0, 0, 0, 0, 2, 0]
[0, 0, 0, 0, 0, 1, 0, 1]
[0, 0, 0, 0, 0, 1, 1, 0]
[0, 0, 0, 0, 0, 2, 0, 0]
[0, 0, 0, 0, 1, 0, 0, 1]
[0, 0, 0, 0, 1, 0, 1, 0]
[0, 0, 0, 0, 1, 1, 0, 0]
[0, 0, 0, 0, 2, 0, 0, 0]
[0, 0, 0, 1, 0, 0, 0, 1]
[0, 0, 0, 1, 0, 0, 1, 0]
[0, 0, 0, 1, 0, 1, 0, 0]
[0, 0, 0, 1, 1, 0, 0, 0]
[0, 0, 0, 2, 0, 0, 0, 0]
[0, 0, 1, 0, 0, 0, 0, 1]
[0, 0, 1, 0, 0, 0, 1, 0]
[0, 0, 1, 0, 0, 1, 0, 0]
[0, 0, 1, 0, 1, 0, 0, 0]
[0, 0, 1, 1, 0, 0, 0, 0]
[0, 0, 2, 0, 0, 0, 0, 0]
[0, 1, 0, 0, 0, 0, 0, 1]
[0, 1, 0, 0, 0, 0, 1, 0]
[0, 1, 0, 0, 0, 1, 0, 0]
[0, 1, 0, 0, 1, 0, 0, 0]
[0, 1, 0, 1, 0, 0, 0, 0]
[0, 1, 1, 0, 0, 0, 0, 0]
[0, 2, 0, 0, 0, 0, 0, 0]
[1, 0, 0, 0, 0, 0, 0, 1]
[1, 0, 0, 0, 0, 0, 1, 0]
[1, 0, 0, 0, 0, 1, 0, 0]
[1, 0, 0, 0, 1, 0, 0, 0]
[1, 0, 0, 1, 0, 0, 0, 0]
[1, 0, 1, 0, 0, 0, 0, 0]
[1, 1, 0, 0, 0, 0, 0, 0]
[2, 0, 0, 0, 0, 0, 0, 0]
		

Crossrefs

Programs

  • Maple
    a:= n-> binomial(n^3+n-1, n): seq(a(n), n=0..16);
  • Mathematica
    Table[Binomial[n^3 + n - 1, n], {n, 0, 13}] (* Michael De Vlieger, Oct 05 2017 *)
  • PARI
    a(n) = binomial(n^3+n-1, n); \\ Altug Alkan, Oct 03 2017

Formula

a(n) = binomial(n^3+n-1, n).
Let denote P(n) = the number of integer partitions of n,
p(i) = the number of parts of the i-th partition of n,
d(i) = the number of different parts of the i-th partition of n,
m(i,j) = multiplicity of the j-th part of the i-th partition of n.
Then one has:
a(n) = Sum_{i=1..P(n)} (n^3)!/((n^3-p(i))!*(Product_{j=1..d(i)} m(i,j)!)).
a(n) = [x^n] 1/(1 - x)^(n^3). - Ilya Gutkovskiy, Oct 03 2017
Showing 1-10 of 10 results.