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.

A376823 Number of colorings of a toroidal n X n grid using exactly three colors under translational symmetry.

Original entry on oeis.org

0, 9, 2022, 2679246, 33887517990, 4169289730628814, 4883659745750360600262, 53651309691205903304049168186, 5474401089420129832016444491921748358, 5153775207320113272335114827748860107542139918, 44553974378043749018442678682265335735181851572329684070
Offset: 1

Views

Author

Andrew Howroyd, Oct 05 2024

Keywords

Crossrefs

Main diagonal of A294685.
Cf. A179043, A184278, A376748 (colors permutable), A376822, A376824, A376825.

Formula

a(n) = A184278(n) - 3*A179043(n) + 3.

A376747 Number of non-isomorphic colorings of a toroidal n X n grid using exactly two swappable colors.

Original entry on oeis.org

0, 4, 31, 2107, 671103, 954459519, 5744387279871, 144115188277194943, 14925010118699132241919, 6338253001141180784480847871, 10985355337065420437221545952731135, 77433143050453552574875182200691073835007, 2213872302702432822841084717014014514981767643135, 256208234097415541381052629523530965709132732687965552639
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 A294791.

Formula

a(n) = (1/(n^2*2!))*(Sum_{sigma in S_2} 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..2} (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.