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 1-3 of 3 results.

A376822 Number of colorings of a toroidal n X n grid using exactly two colors under translational symmetry.

Original entry on oeis.org

0, 5, 62, 4154, 1342206, 1908897150, 11488774559742, 288230376353050814, 29850020237398264483838, 12676506002282327791964489726, 21970710674130840874443091905462270, 154866286100907105149651981766316633972734, 4427744605404865645682169434028029029963535286270
Offset: 1

Views

Author

Andrew Howroyd, Oct 05 2024

Keywords

Crossrefs

Main diagonal of A294684.
Cf. A179043, A376747 (colors permutable), A376823, A376824, A376825.

Formula

a(n) = A179043(n) - 2.

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.

A376749 Number of non-isomorphic colorings of a toroidal n X n grid using exactly four swappable colors.

Original entry on oeis.org

0, 1, 874, 10741819, 1870851589562, 5465007068038102643, 269482732023591671431784330, 221537990355601030571170905795094315, 3007205014171762201565124875608675533096268906, 669557518440386985607930852942771727146772232484581602227, 2433673642945425535196140161775877796522974318753784273286700783313050
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 A294793.

Formula

a(n) = (1/(n^2*4!))*(Sum_{sigma in S_4} 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..4} (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 1-3 of 3 results.