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.

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A052365 Number of nonnegative integer 3 X 3 matrices with sum of elements equal to n, under row and column permutations.

Original entry on oeis.org

1, 1, 4, 10, 24, 51, 114, 219, 424, 768, 1352, 2278, 3759, 5978, 9328, 14181, 21164, 30943, 44560, 63063, 88088, 121321, 165152, 222157, 295857, 389948, 509456, 659697, 847552, 1080452, 1367814, 1719652, 2148596, 2668107, 3294676, 4046069
Offset: 0

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Author

Vladeta Jovovic, Mar 08 2000

Keywords

Comments

Also Molien series for group of structure S_3 X S_3 = (Z_3 X Z_3).O_2^+(3) and order 36, corresponding to complete weight enumerators of Hermitian self-dual GF(3)-linear codes over GF(9) containing the all-ones vector.

Crossrefs

Programs

  • Mathematica
    permcount[v_List] := 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_List, q_List, 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_] := M[3, 3, n];
    a /@ Range[0, 40] (* Jean-François Alcover, Sep 03 2019, after Andrew Howroyd in A318795 *)

Formula

G.f.: -(x^10+2*x^8+x^7+7*x^6-3*x^5+4*x^3+x^2-2*x+1) / ((x^4-x^3+x-1)*(x^3-1)^3*(x+1)^3*(x-1)^5).
Another form for g.f.: u1/u2, where u1 := 1 + x + 2*x^3 + 10*x^4 + 17*x^5 + 19*x^6 + 20*x^7 + 29*x^8 + 37*x^9 + 34*x^10 + 23*x^11 + 12*x^12 + 7*x^13 + 3*x^14 + x^15 u2 := (1-x^2)^4*(1-x^3)^4*(1-x^6);

A053304 Number of 7 X 7 binary matrices with n=0..49 ones up to row and column permutations.

Original entry on oeis.org

1, 1, 3, 6, 16, 34, 90, 211, 515, 1229, 2960, 6893, 15753, 34450, 72235, 143477, 269186, 473945, 781713, 1203617, 1728192, 2310376, 2874232, 3325215, 3576980, 3576980, 3325215, 2874232, 2310376, 1728192, 1203617, 781713, 473945, 269186
Offset: 0

Views

Author

Vladeta Jovovic, Mar 05 2000

Keywords

Crossrefs

Row 7 of A052371 and A321609.

Programs

  • PARI
    \\ See A321609 for M.
    vector(50, n, M(7,7,n-1))

Formula

a(n) = A049311(n) for n <= 7.
Sum_{n=0..49} a(n) = 33642660 = A002724(7).

A122082 Number of unlabeled bicolored graphs on 2n nodes which are invariant when the two color classes are interchanged.

Original entry on oeis.org

1, 2, 5, 16, 67, 404, 3904, 64840, 1930842, 104698904, 10401039400, 1900637187280, 641429385018832, 401454435464761376, 467919402404052870944, 1019758699013228238271040, 4171161230867751509749228304
Offset: 0

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Author

N. J. A. Sloane, Oct 18 2006

Keywords

References

  • R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976.

Crossrefs

Row sums of A123548.

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];
    edges[v_] := Sum[GCD[v[[i]], v[[j]]], {i, 2, Length[v]}, {j, 1, i - 1}] + Total @ Quotient[v + 1, 2]
    a[n_] := (s=0; Do[s += permcount[p]*2^edges[p], {p, IntegerPartitions[n]}]; s/n!);
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Jul 06 2018, after Andrew Howroyd *)
  • PARI
    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}
    edges(v) = {sum(i=2, #v, sum(j=1, i-1, gcd(v[i],v[j]))) + sum(i=1, #v, (v[i]+1)\2)}
    a(n) = {my(s=0); forpart(p=n, s+=permcount(p)*2^edges(p)); s/n!} \\ Andrew Howroyd, Oct 23 2017

Formula

a(n) = 2*A007139(n) - A002724(n). - Vladeta Jovovic, Feb 27 2007

Extensions

More terms from Vladeta Jovovic, Feb 27 2007

A002725 Number of incidence matrices: n X (n+1) binary matrices under row and column permutations.

Original entry on oeis.org

1, 3, 13, 87, 1053, 28576, 2141733, 508147108, 402135275365, 1073376057490373, 9700385489355970183, 298434346895322960005291, 31479360095907908092817694945, 11474377948948020660089085281068730, 14568098446466140788730090352230460100956
Offset: 0

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Author

Keywords

Comments

a(0) = 1 by convention.

Examples

			a(1) = 3: [0,0], [0,1], [1,1].
a(2) = 13:
000 000 000 000 001 001 001 001 001 011 011 011 111
000 001 011 111 001 010 011 110 111 011 101 111 111
		

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

A diagonal of the array A(m,n) described in A028657. - N. J. A. Sloane, Sep 01 2013

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, {0}, `if`(i<1, {},
          {seq(map(p-> p+j*x^i, b(n-i*j, i-1))[], j=0..n/i)}))
        end:
    a:= n-> add(add(2^add(add(igcd(i, j)* coeff(s, x, i)*
          coeff(t, x, j), j=1..degree(t)), i=1..degree(s))/
          mul(i^coeff(s, x, i)*coeff(s, x, i)!, i=1..degree(s))/
          mul(i^coeff(t, x, i)*coeff(t, x, i)!, i=1..degree(t)),
          t=b(n+1$2)), s=b(n$2)):
    seq(a(n), n=0..12);  # Alois P. Heinz, Aug 01 2014
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, {0}, If[i<1, {}, Flatten @ Table[ Map[ Function[ {p}, p+j*x^i], b[n-i*j, i-1]], {j, 0, n/i}]]];
    a[n_] := Sum[Sum[2^Sum[ Sum [ GCD[i, j]*Coefficient[s, x, i]*Coefficient[t, x, j], {j, 1, Exponent[t, x]}], {i, 1, Exponent[s, x]}] / Product[ i^Coefficient[s, x, i]*Coefficient[s, x, i]!, {i, 1, Exponent[s, x]}] / Product[i^Coefficient[t, x, i]*Coefficient[t, x, i]!, {i, 1, Exponent[t, x]}], {t, b[n+1, n+1]}], {s,  b[n, n]}];
    Table[a[n], {n, 0, 12}] (* Jean-François Alcover, Feb 25 2015, after Alois P. Heinz *)
  • PARI
    a(n) = A(n+1,n) \\ A defined in A028657. - Andrew Howroyd, Mar 01 2023

Formula

a(n) = sum_{1*s_1+2*s_2+...=n, 1*t_1+2*t_2+...=n+1} (fix A[s_1, s_2, ...; t_1, t_2, ...]/(1^s_1*s_1!*2^s_2*s_2!*...*1^t_1*t_1!*2^t_2*t_2!*...)) where fix A[...] = 2^sum_{i, j>=1} (gcd(i, j)*s_i*t_j). - Sean A. Irvine, Jul 31 2014

Extensions

More terms from Vladeta Jovovic, Feb 04 2000

A006383 Number of equivalence classes of n X n binary matrices when one can permute rows, permute columns and complement columns.

Original entry on oeis.org

1, 1, 3, 7, 41, 299, 6128, 343656, 67013431, 45770163273, 108577103160005, 886929528971819040, 24943191706060101926577, 2425246700258693990625775794, 820270898724825121532156178527106
Offset: 0

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Author

Keywords

Examples

			a(2) = 3:
00 10 11
00 00 00
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Main diagonal of A363349.

Extensions

Definition corrected by Brendan McKay, Jan 07 2007
Terms a(7) onward from Max Alekseyev, Feb 05 2010

A052269 Number of n X n matrices over GF(3) up to row and column permutations.

Original entry on oeis.org

1, 3, 27, 738, 90492, 64796982, 302752867740, 9610448114487414, 2130536585704570302966, 3379836486315342147630795474, 39197947672609240635681299333726499, 3385559039111928075792568062997302563515455, 2212558055097091715366351569353345370930731329332056
Offset: 0

Views

Author

Vladeta Jovovic, Feb 04 2000

Keywords

Crossrefs

Column k=3 of A246106.

Programs

Formula

a(n) = Sum_{1*s_1+2*s_2+...=n, 1*t_1+2*t_2+...=n} (fixA[s_1, s_2, ...;t_1, t_2, ...]/(1^s_1*s_1!*2^s_2*s_2!*...*1^t_1*t_1!*2^t_2*t_2!*...)) where fixA[...] = 3^Sum_{i, j>=1} (gcd(i,j)*s_i*t_j). - Christian G. Bower, Dec 18 2003

Extensions

More terms from Alois P. Heinz, Jul 31 2014

A052366 Number of nonnegative integer 4 X 4 matrices with sum of elements equal to n, under row and column permutations.

Original entry on oeis.org

1, 1, 4, 10, 33, 78, 224, 549, 1403, 3292, 7677, 16934, 36581, 75732, 152949, 298784, 569636, 1056500, 1916502, 3396630, 5901524, 10051384, 16820192, 27664756, 44795247, 71442327, 112366941, 174384376, 267289440, 404838044, 606375995
Offset: 0

Views

Author

Vladeta Jovovic, Mar 08 2000

Keywords

Crossrefs

Row 4 of A318795.

Formula

G.f.: (x^34 - 4*x^33 + 6*x^32 - x^31 + 3*x^30 - 11*x^29 + 33*x^28 - 19*x^27 + 81*x^26 - 52*x^25 + 152*x^24 - 36*x^23 + 255*x^22 - 130*x^21 + 367*x^20 - 84*x^19 + 350*x^18 - 94*x^17 + 350*x^16 - 84*x^15 + 367*x^14 - 130*x^13 + 255*x^12 - 36*x^11 + 152*x^10 - 52*x^9 + 81*x^8 - 19*x^7 + 33*x^6 - 11*x^5 + 3*x^4 - x^3 + 6*x^2 - 4*x + 1)/((x^10 + x^9 - x^7 - x^6 + x^4 + x^3 - x - 1)*(x^6 - 1)^2*(x^2 + 1)^3*(x^2 - 1)^4*(x^2 + x + 1)^2*(x + 1)*(x - 1)^9).

A052371 Triangle T(n,k) of n X n binary matrices with k=0...n^2 ones up to row and column permutations.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 3, 6, 7, 7, 6, 3, 1, 1, 1, 1, 3, 6, 16, 21, 39, 44, 55, 44, 39, 21, 16, 6, 3, 1, 1, 1, 1, 3, 6, 16, 34, 69, 130, 234, 367, 527, 669, 755, 755, 669, 527, 367, 234, 130, 69, 34, 16, 6, 3, 1, 1
Offset: 0

Views

Author

Vladeta Jovovic, Mar 08 2000

Keywords

Examples

			Triangle begins:
  1;
  1, 1;
  1, 1, 3, 1, 1;
  1, 1, 3, 6, 7, 7, 6, 3, 1, 1;
  1, 1, 3, 6, 16, 21, 39, 44, 55, 44, 39, 21, 16, 6, 3, 1, 1;
  ...
(the last block giving the numbers of 4 X 4 binary matrices with k=0..16 ones up to row and column permutations).
		

Crossrefs

Rows 6..8 are A052370, A053304, A053305.
Row sums are A002724.
Cf. A049311.

Programs

  • Mathematica
    permcount[v_] := Module[{m = 1, s = 0, t, i, k = 0}, 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_] := Product[(1 + x^LCM[p[[i]], q[[j]]])^GCD[p[[i]], q[[j]]], {i, 1, Length[p]}, {j, 1, Length[q]}];
    row[n_] := Module[{s = 0}, Do[Do[s += permcount[p]*permcount[q]*c[p, q], {q, IntegerPartitions[n]}], {p, IntegerPartitions[n]}]; CoefficientList[ s/(n!^2), x]]
    row /@ Range[0, 5] // Flatten (* Jean-François Alcover, Sep 22 2019, after Andrew Howroyd *)
  • PARI
    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}
    c(p, q)={prod(i=1, #p, prod(j=1, #q, (1 + x^lcm(p[i], q[j]))^gcd(p[i], q[j])))}
    row(n)={my(s=0); forpart(p=n, forpart(q=n, s+=permcount(p) * permcount(q) * c(p, q))); Vec(s/(n!^2))}
    for(n=1, 5, print(row(n))) \\ Andrew Howroyd, Nov 14 2018

Extensions

a(0)=1 prepended by Andrew Howroyd, Nov 14 2018

A058001 Number of 3 X 3 matrices with entries mod n, up to row and column permutation.

Original entry on oeis.org

1, 36, 738, 8240, 57675, 289716, 1144836, 3780288, 10865205, 27969700, 65834406, 143887536, 295467263, 575308020, 1069960200, 1911933696, 3298486761, 5516122788, 8972008810, 14233690800, 22078652211, 33555443636, 50058302988, 73417387200, 106006948125
Offset: 1

Views

Author

Vladeta Jovovic, Nov 04 2000

Keywords

Comments

Number of k X l matrices with entries mod n, up to row and column permutation is Z(S_k X S_l; n,n,...) where Z(S_k X S_l; x_1,x_2,...) is cycle index of Cartesian product of symmetric groups S_k and S_l of degree k and l, respectively.

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[x (12x^7+369x^6+2514x^5+4375x^4+2360x^3+423x^2+26x+1)/(x-1)^10,{x,0,30}],x] (* or *) LinearRecurrence[{10,-45,120,-210,252,-210,120,-45,10,-1},{0,1,36,738,8240,57675,289716,1144836,3780288,10865205},30] (* Harvey P. Dale, Nov 23 2024 *)

Formula

a(n) = (1/3!^2)*(n^9 + 6*n^6 + 9*n^5 + 8*n^3 + 12*n^2).
G.f.: x*(12*x^7+369*x^6+2514*x^5+4375*x^4+2360*x^3+423*x^2+26*x+1) / (x-1)^10. - Colin Barker, Jul 09 2013

A058004 Number of 6 X 6 matrices with entries mod n, up to row and column permutation.

Original entry on oeis.org

1, 251610, 302752867740, 9178323524804624, 28125393244553141210, 19909522361922032493690, 5116530046996205504668323, 626072069382507442113224128, 43460016875695276108491159279
Offset: 1

Views

Author

Vladeta Jovovic, Nov 04 2000

Keywords

Comments

Number of k X l matrices with entries mod n, up to row and column permutation is Z(S_k X S_l; n,n,...) where Z(S_k X S_l; x_1,x_2,...) is cycle index of Cartesian product of symmetric groups S_k and S_l of degree k and l, respectively.

Crossrefs

Formula

a(n)=(1/6!^2)*(n^36 + 30*n^30 + 225*n^26 + 170*n^24 + 1350*n^22 + 3225*n^20 + 4075*n^18 + 9900*n^16 + 28500*n^14 + 56048*n^12 + 61020*n^10 + 77616*n^8 + 153840*n^6 + 87840*n^4 + 34560*n^2).
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