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.

A002860 Number of Latin squares of order n; or labeled quasigroups.

Original entry on oeis.org

1, 2, 12, 576, 161280, 812851200, 61479419904000, 108776032459082956800, 5524751496156892842531225600, 9982437658213039871725064756920320000, 776966836171770144107444346734230682311065600000
Offset: 1

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Author

Keywords

Comments

Also the number of minimum vertex colorings in the n X n rook graph. - Eric W. Weisstein, Mar 02 2024

References

  • David Nacin, "Puzzles, Parity Maps, and Plenty of Solutions", Chapter 15, The Mathematics of Various Entertaining Subjects: Volume 3 (2019), Jennifer Beineke & Jason Rosenhouse, eds. Princeton University Press, Princeton and Oxford, p. 245.
  • Clifford A. Pickover, The Math Book, From Pythagoras to the 57th Dimension, 250 Milestones in the History of Mathematics, Sterling Publ., NY, 2009.
  • J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 210.
  • H. J. Ryser, Combinatorial Mathematics. Mathematical Association of America, Carus Mathematical Monograph 14, 1963, p. 53.
  • 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

Cf. A098679 (Latin cubes).
A row of the array in A249026.

Programs

  • Mathematica
    Table[Length[ResourceFunction["FindProperColorings"][GraphProduct[CompleteGraph[n], CompleteGraph[n], "Cartesian"], n]], {n, 5}]

Formula

a(n) = n!*A000479(n) = n!*(n-1)!*A000315(n).

Extensions

One more term (from the McKay-Wanless article) from Richard Bean, Feb 17 2004

A057771 Number of loops (quasigroups with an identity element) of order n.

Original entry on oeis.org

0, 1, 1, 1, 2, 6, 109, 23746, 106228849, 9365022303540, 20890436195945769617, 1478157455158044452849321016
Offset: 0

Views

Author

Christian G. Bower, Nov 01 2000

Keywords

Crossrefs

Extensions

a(8) from Juergen Buntrock (jubu(AT)jubu.com), Nov 03 2003.
a(9)-a(10) (from the McKay-Meynert-Myrvold article) from Richard Bean, Feb 17 2004
a(11) from Petteri Kaski (petteri.kaski(AT)cs.helsinki.fi), Sep 18 2009
a(0) prepended by Jianing Song, Oct 26 2019

A057996 Number of self-converse loops (quasigroups with an identity element) of order n.

Original entry on oeis.org

0, 1, 1, 1, 2, 4, 35, 556, 64065
Offset: 0

Views

Author

Christian G. Bower, Nov 01 2000

Keywords

Comments

x*y is isomorphic to y*x.

Crossrefs

Extensions

a(8) from Juergen Buntrock (jubu(AT)eule.in-berlin.de), Nov 17 2003
Offset corrected and a(0) prepended by Jianing Song, Oct 26 2019

A057994 Number of asymmetric quasigroups of order n.

Original entry on oeis.org

1, 1, 1, 0, 16, 1303, 1127628
Offset: 0

Views

Author

Christian G. Bower, Nov 01 2000

Keywords

Crossrefs

A057992 Number of commutative quasigroups of order n.

Original entry on oeis.org

1, 1, 1, 3, 7, 11, 491, 6381, 10940111, 1225586965, 130025302505741, 252282619993126717, 2209617218725712597768722, 98758655816833782283724345637
Offset: 0

Views

Author

Christian G. Bower, Nov 01 2000

Keywords

Crossrefs

Extensions

Added a(7) = 6381, W. Edwin Clark, Jan 04 2011
a(8)-a(13) from Ian Wanless, Dec 08 2021

A057993 Number of self-converse quasigroups of order n.

Original entry on oeis.org

1, 1, 1, 3, 13, 81, 3883
Offset: 0

Views

Author

Christian G. Bower, Nov 01 2000

Keywords

Crossrefs

A058171 Number of quasigroups of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).

Original entry on oeis.org

1, 1, 1, 4, 24, 746, 567207
Offset: 0

Views

Author

Christian G. Bower, Nov 20 2000

Keywords

Crossrefs

a(n)=(A057991(n)+A057993)/2.

A058175 Triangle: Number of quasigroups of order n with k idempotents.

Original entry on oeis.org

1, 0, 1, 0, 1, 0, 1, 3, 0, 1, 9, 18, 6, 1, 1, 420, 638, 264, 77, 8, 4, 367590, 469675, 227168, 57788, 7712, 580, 18
Offset: 0

Views

Author

Christian G. Bower, Nov 20 2000

Keywords

Examples

			1; 0,1; 0,1,0; 1,3,0,1; 9,18,6,1,1; ...
		

Crossrefs

Row sums give A057991.

A118127 Number of quasigroups of order <= n.

Original entry on oeis.org

1, 2, 3, 8, 43, 1454, 1131985, 12199587820, 2697830531268481, 15224736759268778589978, 2750892227033887206264514123491
Offset: 1

Views

Author

Jonathan Vos Post, May 12 2006

Keywords

Comments

A quasigroup is a groupoid G such that for all a and b in G, there exist unique c and d in G such that ac = b and da = b. Hence a quasigroup is not required to have an identity element, nor be associative. Equivalently, one can state that quasigroups are precisely groupoids whose multiplication tables are Latin squares (possibly empty).

Examples

			a(10) = 2750892227033887206264514123491 = 1 + 1 + 1 + 5 + 35 + 1411 + 1130531 + 12198455835 + 2697818331680661 + 15224734061438247321497 + 2750892211809150446995735533513.
		

Crossrefs

Formula

a(n) = SUM[i=0..n] A057991(i).

A328746 Number of loops of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).

Original entry on oeis.org

0, 1, 1, 1, 2, 5, 72, 12151, 53146457
Offset: 0

Views

Author

Jianing Song, Oct 26 2019

Keywords

Crossrefs

For the number of group-like algebraic structures of order n, see:
Semigroups: A027851 or A001423 (commutative: A001426);
Monoids: A058129 or A058133 (commutative: A058131);
Quasigroups: A057991 or A058171 (commutative: A057992);
Loops: A057771 or this sequence (commutative: A089925);
Groups: A000001 (commutative: A000688);
Rings: A027623 or A038036 (commutative: A037289);
Rings with unity: A037291;
Fields: A069513.

Formula

a(n) = (A057771(n)+A057996(n))/2.
Showing 1-10 of 10 results.