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 1-5 of 5 results.

A000609 Number of threshold functions of n or fewer variables.

Original entry on oeis.org

2, 4, 14, 104, 1882, 94572, 15028134, 8378070864, 17561539552946, 144130531453121108
Offset: 0

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Author

Keywords

Comments

a(n) is also equal to the number of self-dual threshold functions of n+1 or fewer variables. - Alastair D. King, Mar 17 2023.

References

  • Sze-Tsen Hu, Threshold Logic, University of California Press, 1965 see page 57.
  • D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.1.1, p. 79.
  • S. Muroga, Threshold Logic and Its Applications. Wiley, NY, 1971, p. 38, Table 2.3.2. - Row 3.
  • 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).
  • C. Stenson, Weighted voting, threshold functions, and zonotopes, in The Mathematics of Decisions, Elections, and Games, Volume 625 of Contemporary Mathematics Editors Karl-Dieter Crisman, Michael A. Jones, American Mathematical Society, 2014, ISBN 0821898663, 9780821898666

Crossrefs

Formula

a(n) = Sum_{k=0..n} A000615(k)*binomial(n,k) = Sum_{k=0..n} A002079(k)*binomial(n,k)*2^k. Also A002078(n) = (1/2^n)*Sum_{k=0..n} a(k)*binomial(n,k), a(n-1) = Sum_{k=1..n} A002077(k)*binomial(n,k)*2^k, and A002080(n) = (1/2^n)*Sum_{k=1..n} a(k)*binomial(n,k). - Alastair D. King, Mar 17 2023.

Extensions

a(9) from Minfeng Wang, Jun 27 2010

A001532 Number of NP-equivalence classes of self-dual threshold functions of n or fewer variables ; number of majority (i.e., decisive and weighted) games with n players.

Original entry on oeis.org

1, 1, 2, 3, 7, 21, 135, 2470, 175428, 52980624
Offset: 1

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Author

Keywords

References

  • H. M. Gurk and J. R. Isbell. 1959. Simple Solutions. In A. W. Tucker and R. D. Luce (eds.) Contributions to the Theory of Games, Volume 4. Princeton, NJ: Princeton University Press, pp. 247-265. (Case n=6.)
  • D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.1.1, p. 79.
  • S. Muroga, Threshold Logic and Its Applications. Wiley, NY, 1971, p. 38, Table 2.3.2. - Row 23. (Cases until n=9.)
  • 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).
  • J. von Neumann and O. Morgenstern, Theory of games and economic behavior, Princeton University Press, New Jersey, 1944. (Cases n=1 to 5.)

Crossrefs

Formula

a(n) = Sum_{k=1..n} A003184(k). - Alastair D. King, Oct 26 2023

Extensions

a(10) added by W. Lan (wl(AT)fjrtvu.edu.cn), Jun 27 2010
Better description from Alastair King, Mar 17 2023.

A189359 Number of homogeneous games for n players.

Original entry on oeis.org

0, 1, 3, 8, 23, 76, 293, 1307, 6642, 37882
Offset: 0

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Author

Fabián Riquelme, Apr 20 2011

Keywords

Crossrefs

Subclass of A000617. Cf. A001532, A022493, A109456, A132183.

Formula

Conjecture: g.f.: Q(0)*x/(1-x), where Q(k) = 1 + (1-(1-x)^(2*k+2))/(1- (1-(1-x)^(2*k+3))/(1-(1-x)^(2*k+3) + 1/Q(k+1))); (continued fraction). - Sergei N. Gladkovskii, May 13 2013
Note that a(n) - a(n-1) = A022493(n) for 1 <= n <= 9. Does this equality hold for n > 9? If so, then we have the g.f. 1/(1 - x)*( Sum_{n >= 1} Product_{k = 1..n} (1 - (1 - x)^k) ). - Peter Bala, Dec 13 2021

A189360 Number of self-dual homogeneous games for n players.

Original entry on oeis.org

0, 1, 1, 2, 3, 7, 21, 132, 2188
Offset: 0

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Author

Fabián Riquelme, Apr 20 2011

Keywords

Comments

Found by F. Riquelme

Crossrefs

Intersection of A189359 and A109456.

A290946 Number of chambers of Hassett's decomposition of the weight domain of the moduli space of genus 0 n-pointed curves.

Original entry on oeis.org

1, 27, 1087, 105123, 31562520, 33924554539, 140306938682875
Offset: 3

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Author

Connor Halleck-Dube, Oct 20 2017

Keywords

Comments

a(n) is also the number of goldilocks linear threshold functions on n variables. Asymptotically equal to the total number of linear threshold functions on n variables, divided by 2^n.

Crossrefs

Formula

a(n) ~ 2^(n^2 - n log n + O(n)).
Showing 1-5 of 5 results.