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 1-6 of 6 results.

A059079 Number of n-element T_0-antichains on a labeled set.

Original entry on oeis.org

2, 5, 19, 16654, 2369110564675, 5960531437586238714806902334250676, 479047836152505670895481840783987408043359908583921478726185296900312296071642855730299
Offset: 0

Views

Author

Vladeta Jovovic, Goran Kilibarda, Dec 23 2000

Keywords

Comments

An antichain on a set is a T_0-antichain if for every two distinct points of the set there exists a member of the antichain containing one but not the other point.

Examples

			a(0) = (1/0!)*[1!*e] = 2; a(1) = (1/1!)*[2!*e] = 5; a(2) = (1/2!)*([4!*e] - 2*[3!*e] + [2!*e]) = 19; a(3) = (1/3!)*([8!*e] - 6*[6!*e] + 6*[5!*e] + 3*[4!*e] - 6*[3!*e] + 2*[2!*e]) = 16654, where [n!*e]=floor(n!*exp(1)).
		

References

  • V. Jovovic and G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6)
  • V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.

Crossrefs

A059080 Triangle A(n,m) of numbers of n-element T_0-antichains on a labeled m-set, m=0,...,2^n.

Original entry on oeis.org

1, 1, 1, 2, 2, 0, 0, 1, 6, 12, 0, 0, 0, 2, 52, 520, 2640, 6720, 6720, 0, 0, 0, 0, 25, 1770, 53940, 1012620, 13487040, 136745280, 1094688000, 7025356800, 36084787200, 145297152000, 435891456000, 871782912000, 871782912000
Offset: 0

Views

Author

Vladeta Jovovic, Goran Kilibarda, Dec 29 2000

Keywords

Comments

An antichain on a set is a T_0-antichain if for every two distinct points of the set there exists a member of the antichain containing one but not the other point. Row sums give A059079. Column sums give A059083.

Examples

			[1, 1], [1, 2, 2], [0, 0, 1, 6, 12], [0, 0, 0, 2, 52, 520, 2640, 6720, 6720], ...; there are 2 3-element T_0-antichains on a 3-set: {{1}, {2}, {3}}, {{1, 2}, {1, 3}, {2, 3}}.
		

References

  • V. Jovovic and G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6)
  • V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.

Crossrefs

A059081 Number of 5-element T_0-antichains on a labeled n-set, n=0,..,32.

Original entry on oeis.org

0, 0, 0, 0, 6, 2086, 273072, 19371912, 940055760, 35289051840, 1099827892800, 29723466326400, 716351882400000, 15683016533184000, 315722887044364800, 5890186860509952000, 102288867798813696000, 1656523525703574528000
Offset: 0

Views

Author

Vladeta Jovovic, Goran Kilibarda, Jan 06 2001

Keywords

Comments

An antichain on a set is a T_0-antichain if for every two distinct points of the set there exists a member of the antichain containing one but not the other point.

References

  • V. Jovovic and G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6)
  • V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.

Crossrefs

Programs

  • Mathematica
    P[x_, n_] := (-1)^n*Pochhammer[-x, n]; Table[(1/5!)*(P[32, n] - 20*P[24, n] + 60*P[20, n] + 20*P[18, n] + 10*P[17, n] - 110*P[16, n] - 120*P[15, n] + 150*P[14, n] + 120*P[13, n] - 240*P[12, n] + 20*P[11, n] + 240*P[10, n] + 40*P[9, n] - 205*P[8, n] + 60*P[7, n] - 210*P[6, n] + 210*P[5, n] + 50*P[4, n] - 100*P[3, n] + 24*P[2, n]), {n, 0, 32}] (* G. C. Greubel, Oct 07 2017 *)

Formula

a(n) = (1/5!)*([32]_n - 20*[24]_n + 60*[20]_n + 20*[18]_n + 10*[17]_n - 110*[16]_n - 120*[15]_n + 150*[14]_n + 120*[13]_n - 240*[12]_n + 20*[11]_n + 240*[10]_n + 40*[9]_n - 205*[8]_n + 60*[7]_n - 210*[6]_n + 210*[5]_n + 50*[4]_n - 100*[3]_n + 24*[2]_n), where [k]_n := k*(k - 1)*...*(k - n + 1), [k]_0 = 1.

A059082 Number of 6-element T_0-antichains on a labeled n-set, n = 0, ..., 64.

Original entry on oeis.org

0, 0, 0, 0, 1, 1370, 738842, 176796382, 26021566536, 2807549333568, 245222809302240, 18418417704308160, 1236761946163054080, 76210520306627266560, 4388527139331858082560, 239214759548062858560000, 12457699161320493400320000, 623967599346727576292352000
Offset: 0

Views

Author

Vladeta Jovovic, Goran Kilibarda, Jan 06 2001

Keywords

Comments

An antichain on a set is a T_0-antichain if for every two distinct points of the set there exists a member of the antichain containing one but not the other point.

References

  • V. Jovovic and G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6)
  • V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.

Crossrefs

Programs

  • Maple
    f:=proc(k,n) if k+1<=n then RETURN(0) else RETURN(k!/(k - n)!) fi: end;a:=n->(1/6!)*(f(64,n) - 30*f(48,n) + 120*f(40,n) + 60*f(36,n) + 60*f(34,n)- 12*f(33,n) - 345*f(32,n) - 720*f(30,n) + 810*f(28,n) + 120*f(27,n) + 480*f(26,n) + 360*f(25,n) - 480*f(24,n) - 720*f(23,n) - 240*f(22,n) - 540*f(21,n) + 1380*f(20,n) + 750*f(19,n) + 60*f(18,n) - 210*f(17,n) - 1535*f(16,n) - 1820*f(15,n) + 2250*f(14,n) + 1800*f(13,n) - 2820*f(12,n) + 300*f(11,n) + 2040*f(10,n) + 340*f(9,n) - 1815*f(8,n) + 510*f(7,n) - 1350*f(6,n) + 1350*f(5,n) + 274*f(4,n) - 548*f(3,n) + 120*f(2,n));seq(a(n),n=0..20); # Pab Ter (pabrlos2(AT)yahoo.com), Nov 06 2005

Formula

a(n) = (1/6!)*([64]_n - 30*[48]_n + 120*[40]_n + 60*[36]_n + 60*[34]_n - 12*[33]_n - 345*[32]_n - 720*[30]_n + 810*[28]_n + 120*[27]_n + 480*[26]_n + 360*[25]_n - 480*[24]_n - 720*[23]_n - 240*[22]_n - 540*[21]_n + 1380*[20]_n + 750*[19]_n + 60*[18]_n - 210*[17]_n - 1535*[16]_n - 1820*[15]_n + 2250*[14]_n + 1800*[13]_n - 2820*[12]_n + 300*[11]_n + 2040*[10]_n + 340*[9]_n - 1815*[8]_n + 510*[7]_n - 1350*[6]_n + 1350*[5]_n + 274*[4]_n - 548*[3]_n + 120*[2]_n), where [k]_n := k*(k - 1)*...*(k - n + 1), [k]_0 = 1.

Extensions

More terms from Pab Ter (pabrlos2(AT)yahoo.com), Nov 06 2005

A088888 Number of intersecting T_0-hypergraphs on a labeled n-set.

Original entry on oeis.org

2, 4, 26, 1190, 1302204, 912799349556, 291201248247281713961832
Offset: 1

Views

Author

Goran Kilibarda, Vladeta Jovovic, Nov 28 2003

Keywords

Comments

Intersecting hypergraph is intersecting T_0-hypergraph if for every two distinct nodes there exists a hyperedge containing one but not the other node.

Crossrefs

A088895 Number of intersecting T_0-antichains on a labeled n-set.

Original entry on oeis.org

1, 2, 2, 4, 41, 2104, 1387915, 229780525655
Offset: 0

Views

Author

Goran Kilibarda, Vladeta Jovovic, Nov 28 2003

Keywords

Comments

An antichain on a set is a T_0-antichain if for every two distinct pointsf the set there exists a member of the antichain containing one but not the other point.

Crossrefs

Showing 1-6 of 6 results.