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.

A007695 Cardinalities of Sperner families on 1,...,n.

Original entry on oeis.org

2, 3, 5, 10, 26, 96, 553, 5461, 100709, 3718354, 289725509, 49513793526, 19089032278261, 16951604697397302, 35231087224279091310, 173550485517380958360611, 2047581288200721764035942914
Offset: 0

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Author

Keywords

Comments

Also number of f-vectors for simplicial complexes on at most n vertices.

References

  • S. Johnson, Upper bounds for constant weight error correcting codes, Discrete Math., 3 (1972), 109-124.
  • D. E. Knuth, The Art of Computer Programming, vol. 4A, Combinatorial Algorithms, Section 7.2.1.3 (p. 743).
  • D. E. Knuth, Art of Computer Programming, Vol. 4, Section 7.3, to appear.
  • S. Linusson, The number of M-sequences and f-vectors, Combinatorica, 19 (1999), 255-266.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

This is the limiting form of A011828-A011833.
Cf. A001405.

Programs

  • Mathematica
    c[ 0, 0 ]=1; c[ 0, 1 ]=1; kap[ 0, 0 ]=0; f[ n_ ] := Block[ {s=2, r, d, k, j}, For[ r=1, r<=n, r++, d=s; k=r; j=0; s=0;
    For[ x=0, x<=Binomial[ n, r ], x++, If[ x>=Binomial[ k, r ], k++, 0 ]; kap[ r, x ]=If[ x==0, 0, Binomial[ k-1, r-1 ]+kap[ r-1, x-Binomial[ k-1, r ] ] ];
    While[ j
    				

Extensions

Entry revised by N. J. A. Sloane, Sep 03 2011

A011820 Number of M-sequences m_0,...,m_4 with m_1 < n.

Original entry on oeis.org

2, 6, 32, 203, 1144, 5345, 20926, 70506, 209746, 562727, 1384758, 3167606, 6807620, 13863904, 26941700, 50245591, 90358146, 157312324, 266040452, 438299013, 705186944, 1110395771, 1714352818, 2599444040, 3876530866
Offset: 0

Views

Author

Svante Linusson (linusson(AT)math.kth.se)

Keywords

References

  • S. Linusson, The number of M-sequences and f-vectors, Combinatorica, 19 (1999), 255-266.

Crossrefs

Programs

  • PARI
    a(n)=n*(4*n^9+61*n^8+408*n^7+1722*n^6+6132*n^5+18333*n^4+41072*n^3 +88748*n^2 +133824*n+193536)/120960+2 \\ Charles R Greathouse IV, Dec 08 2011

Formula

a(n) = ( 4*n^10 +61*n^9 +408*n^8 +1722*n^7 +6132*n^6 +18333*n^5 +41072*n^4 +88748*n^3 +133824*n^2 +193536*n +241920 )/120960. - Frank Ellermann
G.f.: -x*(x^10 -11*x^9 +53*x^8 -147*x^7 +268*x^6 -298*x^5 +341*x^4 -149*x^3 +76*x^2 -16*x +2) / (x-1)^11. - Colin Barker, Feb 15 2014

A011829 Number of f-vectors for simplicial complexes of dimension at most 4 on at most n-1 vertices.

Original entry on oeis.org

2, 3, 5, 10, 26, 96, 552, 4908, 48230, 398663, 2631241, 14192097, 64663638, 256174350, 902972232, 2883651027, 8463753978, 23094833355, 59133598085, 143164108028, 329810868994, 726833391860, 1539215246944, 3144340388550
Offset: 1

Views

Author

Svante Linusson (linusson(AT)math.kth.se)

Keywords

Comments

Apparently a polynomial (n^15)/32659200 + .... [Frank Ellermann]

References

  • D. E. Knuth, The Art of Computer Programming, vol. 4A, Combinatorial Algorithms, Section 7.2.1.3 (p. 743).
  • S. Linusson, The number of M-sequences and f-vectors, Combinatorica, 19 (1999), 255-266.

Crossrefs

Formula

Empirical G.f.: -x*(x^15 -16*x^14 +114*x^13 -1154*x^12 -2541*x^11 -16919*x^10 -6585*x^9 -17282*x^8 +9460*x^7 -8548*x^6 +5196*x^5 -2426*x^4 +830*x^3 -197*x^2 +29*x -2)/(x -1)^16. [Colin Barker, Sep 18 2012]
Showing 1-3 of 3 results.