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.

A294791 Triangle read by rows, 1 <= k <= n: T(n,k) = non-isomorphic colorings of a toroidal n X k grid using exactly two colors under translational symmetry and swappable colors.

Original entry on oeis.org

0, 1, 4, 1, 7, 31, 3, 23, 179, 2107, 3, 55, 1095, 26271, 671103, 7, 189, 7327, 350063, 17896831, 954459519, 9, 595, 49939, 4794087, 490853415, 52357746895, 5744387279871, 19, 2101, 349715, 67115111, 13743921631, 2932032057731, 643371380132743, 144115188277194943, 29, 7315, 2485591, 954444607, 390937468407, 166799988703927, 73201365371896619
Offset: 1

Views

Author

Marko Riedel, Nov 08 2017

Keywords

Comments

Two colorings are equivalent if there is a permutation of the colors that takes one to the other in addition to translational symmetries on the torus. (Power Group Enumeration.)

Examples

			For the 2 X 2 grid and two colors we find T(2,2) = 4:
  +---+  +---+  +---+  +---+
  |X| |  |X| |  |X|X|  |X| |
  +-+-+  +-+-+  +-+-+  +-+-+
  | | |  | |X|  | | |  |X| |
  +-+-+  +-+-+  +-+-+  +-+-+
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Formula

T(n,k) = (1/(n*k*Q!))*(Sum_{sigma in S_Q} Sum_{d|n} Sum_{f|k} phi(d) phi(f) [[forall j_l(sigma) > 0 : l|lcm(d,f) ]] P(gcd(d,f)*(n/d)*(k/f), sigma)) where P(F, sigma) = F! [z^F] Product_{l=1..Q} (exp(lz)-1)^j_l(sigma) with Q=2. The notation j_l(sigma) is from the Harary text and gives the number of cycles of length l in the permutation sigma. [[.]] is an Iverson bracket.

A294793 Triangle read by rows, 1 <= k <= n: T(n,k) = non-isomorphic colorings of a toroidal n X k grid using exactly four colors under translational symmetry and swappable colors.

Original entry on oeis.org

0, 0, 1, 0, 13, 874, 1, 235, 51075, 10741819, 2, 3437, 2823766, 2261625725, 1870851589562, 13, 51275, 155495153, 486711524815, 1600136051453135, 5465007068038102643, 50, 742651, 8643289534, 107092397450897, 1405227969932349726, 19188864521773558375127, 269482732023591671431784330, 221, 10741763, 486710971595, 24009547064476683
Offset: 1

Views

Author

Marko Riedel, Nov 08 2017

Keywords

Comments

Two colorings are equivalent if there is a permutation of the colors that takes one to the other in addition to translational symmetries on the torus. (Power Group Enumeration.)

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Formula

T(n,k) = (1/(n*k*Q!))*(Sum_{sigma in S_Q} Sum_{d|n} Sum_{f|k} phi(d) phi(f) [[forall j_l(sigma) > 0 : l|lcm(d,f) ]] P(gcd(d,f)*(n/d)*(k/f), sigma)) where P(F, sigma) = F! [z^F] Product_{l=1..Q} (exp(lz)-1)^j_l(sigma) with Q=4. The notation j_l(sigma) is from the Harary text and gives the number of cycles of length l in the permutation sigma. [[.]] is an Iverson bracket.

A294684 Triangle read by rows: T(n,k) is the number of non-isomorphic colorings of a toroidal n X k grid using exactly two colors under translational symmetry, 1 <= k <= n.

Original entry on oeis.org

0, 1, 5, 2, 12, 62, 4, 38, 350, 4154, 6, 106, 2190, 52486, 1342206, 12, 360, 14622, 699598, 35792566, 1908897150, 18, 1180, 99878, 9587578, 981706830, 104715443850, 11488774559742, 34, 4148, 699250, 134223974, 27487816990, 5864063066498, 1286742755471398, 288230376353050814
Offset: 1

Views

Author

Marko Riedel, Nov 06 2017

Keywords

Comments

Colors are not being permuted, i.e., Power Group Enumeration does not apply here.

Examples

			Triangle begins:
   0;
   1,    5;
   2,   12,    62;
   4,   38,   350,    4154;
   6,  106,  2190,   52486,   1342206;
  12,  360, 14622,  699598,  35792566,   1908897150;
  18, 1180, 99878, 9587578, 981706830, 104715443850, 11488774559742;
  ...
For the 2 X 2 and two colors we find
  +---+  +---+  +---+  +---+  +---+
  |X| |  | |X|  |X| |  |X|X|  |X| |
  +-+-+  +-+-+  +-+-+  +-+-+  +-+-+
  | | |  |X|X|  | |X|  | | |  |X| |
  +-+-+  +-+-+  +-+-+  +-+-+  +-+-+
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Main diagonal is A376822.

Programs

  • Mathematica
    With[{Q = 2}, Table[(Q!/n/k) Sum[Sum[EulerPhi[d] EulerPhi[f] StirlingS2[GCD[d, f] (n/d) (k/f), Q], {f, Divisors@ k}], {d, Divisors@ n}], {n, 8}, {k, n}]] // Flatten (* Michael De Vlieger, Nov 08 2017 *)
  • PARI
    T(n,m) = {2*sumdiv(n, d, sumdiv(m, e, eulerphi(d) * eulerphi(e) * stirling(n*m/lcm(d,e), 2, 2) ))/(n*m)} \\ Andrew Howroyd, Oct 05 2024

Formula

T(n,k) = (Q!/(n*k))*(Sum_{d|n} Sum_{f|k} phi(d) phi(f) S(gcd(d,f)*(n/d)*(k/f), Q)) with Q=2 and S(n,k) Stirling numbers of the second kind.
T(n,k) = A184271(n,k) - 2. - Andrew Howroyd, Oct 05 2024

A294685 Triangle read by rows: T(n,k) is the number of non-isomorphic colorings of a toroidal n X k grid using exactly three colors under translational symmetry, 1 <= k <= n.

Original entry on oeis.org

0, 0, 9, 2, 91, 2022, 9, 738, 43315, 2679246, 30, 5613, 950062, 174184755, 33887517990, 91, 43404, 21480921, 11765865678, 6862930841141, 4169289730628814, 258, 338259, 497812638, 816999710223, 1429469771994078, 2605213713043722909, 4883659745750360600262, 729, 2679228, 11765822365, 57906482267826, 303941554100145501
Offset: 1

Views

Author

Marko Riedel, Nov 06 2017

Keywords

Comments

Colors are not being permuted, i.e., Power Group Enumeration does not apply here.

Examples

			Triangle begins:
   0;
   0,     9;
   2,    91,     2022;
   9,   738,    43315,     2679246;
  30,  5613,   950062,   174184755,   33887517990;
  91, 43404, 21480921, 11765865678, 6862930841141, 4169289730628814;
  ...
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Main diagonal is A376823.

Programs

  • PARI
    T(n,m)=6*sumdiv(n, d, sumdiv(m, e, eulerphi(d) * eulerphi(e) * stirling(n*m/lcm(d,e), 3, 2) ))/(n*m) \\ Andrew Howroyd, Oct 05 2024

Formula

T(n,k) = (Q!/(n*k))*(Sum_{d|n} Sum_{f|k} phi(d) phi(f) S(gcd(d,f)*(n/d)*(k/f), Q)) with Q=3 and S(n,k) Stirling numbers of the second kind.
T(n,k) = A184284(n,k) - 3*A184271(n,k) + 3. - Andrew Howroyd, Oct 05 2024

A294686 Triangle read by rows: T(n,k) is the number of non-isomorphic colorings of a toroidal n X k grid using exactly four colors under translational symmetry, 1 <= k <= n.

Original entry on oeis.org

0, 0, 6, 0, 260, 20720, 6, 5112, 1223136, 257706024, 48, 81876, 67769552, 54278580036, 44900438149488, 260, 1223396, 3731753700, 11681058472672, 38403264917970196, 131160169581733489616, 1200, 17815020, 207438938000, 2570217454576416, 33725471278376393424, 460532748521625850986660, 6467585568566200114362823920, 5106, 257706012, 11681057249536, 576229125971686224
Offset: 1

Views

Author

Marko Riedel, Nov 06 2017

Keywords

Comments

Colors are not being permuted, i.e., Power Group Enumeration does not apply here.

Examples

			Triangle begins:
    0;
    0,       6;
    0,     260,      20720;
    6,    5112,    1223136,      257706024;
   48,   81876,   67769552,    54278580036,    44900438149488;
  260, 1223396, 3731753700, 11681058472672, 38403264917970196, 131160169581733489616;
  ...
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Main diagonal is A376824.

Programs

  • PARI
    T(n,m)=my(k=4); k!*sumdiv(n, d, sumdiv(m, e, eulerphi(d) * eulerphi(e) * stirling(n*m/lcm(d,e), k, 2) ))/(n*m) \\ Andrew Howroyd, Oct 05 2024

Formula

T(n,k) = (Q!/(n*k))*(Sum_{d|n} Sum_{f|k} phi(d) phi(f) S(gcd(d,f)*(n/d)*(k/f), Q)) with Q=4 and S(n,k) Stirling numbers of the second kind.
T(n,k) = A184277(n,k) - 4*A184284(n,k) + 6*A184271(n,k) - 4. - Andrew Howroyd, Oct 05 2024

A294687 Triangle read by rows: T(n,k) is the number of non-isomorphic colorings of a toroidal n X k grid using exactly five colors under translational symmetry, 1 <= k <= n.

Original entry on oeis.org

0, 0, 0, 0, 300, 92680, 0, 15750, 13794150, 8221452750, 24, 510312, 1686135376, 4495236798162, 11696087875731720, 300, 13794450, 193054017440, 2425003938178050, 30852000867277668428, 403564024914127655401650, 2400, 343501500, 21664357535320, 1317601563731383350, 82985159653854019928352, 5411356249329837891442095560
Offset: 1

Views

Author

Marko Riedel, Nov 06 2017

Keywords

Comments

Colors are not being permuted, i.e., Power Group Enumeration does not apply here.

Examples

			Triangle begins:
   0;
   0,      0;
   0,    300,      92680;
   0,  15750,   13794150,    8221452750;
  24, 510312, 1686135376, 4495236798162, 11696087875731720;
  ...
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Main diagonal is A376825.

Programs

  • PARI
    T(n,m)=my(k=5); k!*sumdiv(n, d, sumdiv(m, e, eulerphi(d) * eulerphi(e) * stirling(n*m/lcm(d,e), k, 2) ))/(n*m) \\ Andrew Howroyd, Oct 05 2024

Formula

T(n,k) = (Q!/(n*k))*(Sum_{d|n} Sum_{f|k} phi(d) phi(f) S(gcd(d,f)*(n/d)*(k/f), Q)) with Q=5 and S(n,k) Stirling numbers of the second kind.

A294794 Triangle read by rows, 1 <= k <= n: T(n,k) = non-isomorphic colorings of a toroidal n X k grid using exactly five colors under translational symmetry and swappable colors.

Original entry on oeis.org

0, 0, 0, 0, 3, 775, 0, 145, 115100, 68522769, 1, 4281, 14051164, 37460388596, 97467398965031, 3, 115381, 1608801153, 20208371722051, 257100007425866689, 3363033541015148835823, 20, 2863227, 180536313547, 10980013072900632, 691542997115450167856, 45094635411084308447578413, 3020745549854628001139950947779, 136, 68522707
Offset: 1

Views

Author

Marko Riedel, Nov 08 2017

Keywords

Comments

Two colorings are equivalent if there is a permutation of the colors that takes one to the other in addition to translational symmetries on the torus. (Power Group Enumeration.)

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Formula

T(n,k) = (1/(n*k*Q!))*(Sum_{sigma in S_Q} Sum_{d|n} Sum_{f|k} phi(d) phi(f) [[forall j_l(sigma) > 0 : l|lcm(d,f) ]] P(gcd(d,f)*(n/d)*(k/f), sigma)) where P(F, sigma) = F! [z^F] Product_{l=1..Q} (exp(lz)-1)^j_l(sigma) with Q=5. The notation j_l(sigma) is from the Harary text and gives the number of cycles of length l in the permutation sigma. [[.]] is an Iverson bracket.

A295197 Triangle read by rows: T(n,k) is the number of non-isomorphic colorings of a toroidal n X k grid using any number of swappable colors, 1 <= k <= n.

Original entry on oeis.org

1, 2, 9, 3, 43, 2387, 7, 587, 351773, 655089857, 12, 11703, 92197523, 2586209749712, 185543613289205809, 43, 352902, 37893376167, 18581620064907130, 28224967150633208580385, 106103186941524316132396201360, 127, 13639372, 22612848403571, 220019264470242220839, 8045720086273150473238405274, 851013076163633746725692124186472539, 218900758256599151027392153440612298654753249
Offset: 1

Views

Author

Marko Riedel, Nov 16 2017

Keywords

Comments

Two colorings are equivalent if there is a permutation of the colors that takes one to the other in addition to translational symmetries on the torus. (Power Group Enumeration.) Maximum number of colors is n * k.

Examples

			The two-by-two with swappable colors has one monochrome coloring, four colorings with two colors, three colorings with three colors (determined by the color that appears twice) and one coloring with four colors.
Triangle begins:
   1;
   2,     9;
   3,    43,     2387;
   7,   587,   351773,     655089857;
  12, 11703, 92197523, 2586209749712, 185543613289205809;
  ...
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Main diagonal is A376808.

Programs

  • PARI
    \\ B(m,n) is A162663(n,m).
    B(m,n)={n!*polcoef(exp(sumdiv(m,d, (exp(d*x + O(x*x^n))-1)/d)), n)}
    T(n,k)={my(v=vector(lcm(n,k))); fordiv(n,d, fordiv(k,e, v[lcm(d,e)] += eulerphi(d) * eulerphi(e) )); sumdiv(#v, g, v[g]*B(g,n*k/g))/(n*k)} \\ Andrew Howroyd, Oct 06 2024

Formula

T(n,k) = Sum_{Q=1..n*k} (1/(n*k*Q!))*(Sum_{sigma in S_Q} Sum_{d|n} Sum_{f|k} phi(d) phi(f) [[forall j_l(sigma) > 0 : l|lcm(d,f) ]] P(gcd(d,f)*(n/d)*(k/f), sigma)) where P(F, sigma) = F! [z^F] Product_{l=1..Q} (exp(lz)-1)^j_l(sigma). The notation j_l(sigma) is from the Harary text and gives the number of cycles of length l in the permutation sigma. [[.]] is an Iverson bracket.
T(n,k) = (Sum_{d|n} Sum_{f|k} phi(d) * phi(f) * A162663(n*k/lcm(d,f), lcm(d,f)))/(n*k). - Andrew Howroyd, Oct 06 2024

A376808 Number of non-isomorphic colorings of a toroidal n X n grid using any number of swappable colors.

Original entry on oeis.org

1, 9, 2387, 655089857, 185543613289205809, 106103186941524316132396201360, 218900758256599151027392153440612298654753249, 2689595989958732045849530682270318547733917269644639109073775285
Offset: 1

Views

Author

Marko Riedel, Oct 04 2024

Keywords

Comments

Two colorings are equivalent if there is a permutation of the colors that takes one to the other in addition to translational symmetries on the torus (Power Group Enumeration). The maximum number of colors is n * n.

Examples

			For the 2x2 we find
  +-+-+   +-+-+   +-+-+   +-+-+   +-+-+
  |X|X|   |X|X|   |X|X|   |X| |   |X| |
  +-+-+   +-+-+   +-+-+   +-+-+   +-+-+
  |X|X|   |X| |   | | |   |X| |   | |X|
  +-+-+   +-+-+   +-+-+   +-+-+   +-+-+
  +-+-+   +-+-+   +-+-+   +-+-+
  |X|Y|   |X| |   |X| |   |X|Y|
  +-+-+   +-+-+   +-+-+   +-+-+
  | | |   |Y| |   | |Y|   |Z| |
  +-+-+   +-+-+   +-+-+   +-+-+
so a(2) = 9.
		

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Main diagonal of A295197.

Formula

a(n) = Sum_{Q=1..n^2} (1/(n^2*Q!))*(Sum_{sigma in S_Q} Sum_{d|n} Sum_{f|n} phi(d) phi(f) [[forall j_l(sigma) > 0 : l|lcm(d,f) ]] P(gcd(d,f)*(n/d)*(n/f), sigma)) where P(F, sigma) = F! [z^F] Product_{l=1..Q} (exp(lz)-1)^j_l(sigma). The notation j_l(sigma) is from the Harary text and gives the number of cycles of length l in the permutation sigma. [[.]] is an Iverson bracket.

A376748 Number of non-isomorphic colorings of a toroidal n X n grid using exactly three swappable colors.

Original entry on oeis.org

0, 3, 345, 447156, 5647919665, 694881637942816, 813943290958393433377, 8941884948534360647405572800, 912400181570021638669407666368774097, 858962534553352212055863239761275173880606456, 7425662396340624836407113113710889289196975262054947345, 587417576454184723055270940786413231085263155884260701824558793960
Offset: 1

Views

Author

Marko Riedel, Oct 03 2024

Keywords

References

  • F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973.

Crossrefs

Main diagonal of A294792.

Formula

a(n) = (1/(n^2*3!))*(Sum_{sigma in S_3} Sum_{d|n} Sum_{f|n} phi(d) phi(f) [[forall j_l(sigma) > 0 : l|lcm(d,f) ]] P(gcd(d,f)*(n/d)*(n/f), sigma)) where P(F, sigma) = F! [z^F] Product_{l=1..3} (exp(lz)-1)^j_l(sigma). The notation j_l(sigma) is from the Harary text and gives the number of cycles of length l in the permutation sigma. [[.]] is an Iverson bracket.
Showing 1-10 of 10 results.