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 14 results. Next

A002501 a(n) = 7^n - 3*4^n + 2*3^n.

Original entry on oeis.org

1, 19, 205, 1795, 14221, 106819, 778765, 5581315, 39606541, 279447619, 1965098125, 13792018435, 96690872461, 677427332419, 4744368982285, 33220131761155, 232579232659981, 1628208214321219, 11398072876175245, 79788974736297475, 558532690864457101
Offset: 1

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Author

Keywords

Comments

Counts connected relations. On page 578 Kreweras (1969) says: "Le théorème s'applique notamment au dénombrement des relations binaires externes qui possèdent la propriété de connexité; cela revient à calculer le nombre a(m,n) de manières de remplir un tableau de m lignes et n colonnes avec des 0 et des 1, en respectant les deux conditions suivantes: (1): aucune rangée (ligne ni colonne) ne doit être tout entière remplie de zéros; (2): deux cases quelconques marquées 1 peuvent être jointes par une chaîne de cases marquées 1 telle que deux cases consécutives de la chaîne appartiennent à une même rangée."

References

  • 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

A diagonal of A262307.

Programs

Formula

G.f.: -x*(1+5*x) / ( (3*x-1)*(7*x-1)*(4*x-1) ). - R. J. Mathar, Jun 09 2013
a(n) = 14*a(n-1) - 61*a(n-2) + 84*a(n-3). - Wesley Ivan Hurt, Apr 11 2022

Extensions

Better definition and more terms from Goran Kilibarda, Vladeta Jovovic, Apr 14 2004

A002502 Number of connected relations.

Original entry on oeis.org

1, 65, 1795, 36317, 636331, 10365005, 162470155, 2495037197, 37898120011, 572284920845, 8614868501515, 129467758660877, 1943971108806091, 29175170378428685, 437752102106036875, 6567275797761209357
Offset: 1

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Author

Keywords

References

  • 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

A diagonal of A262307.

Programs

  • Mathematica
    LinearRecurrence[{38,-539,3622,-11640,14400},{1,65,1795,36317,636331},20] (* Harvey P. Dale, Mar 24 2017 *)

Formula

15^n-4*8^n-3*6^n+12*5^n-6*4^n. - Goran Kilibarda, Vladeta Jovovic, Apr 14 2004
G.f. x*( -1-27*x+136*x^2+480*x^3 ) / ( (6*x-1)*(5*x-1)*(15*x-1)*(4*x-1)*(8*x-1) ).
- R. J. Mathar, Jun 09 2013

Extensions

More terms from Goran Kilibarda, Vladeta Jovovic, Apr 14 2004

A093733 Number of connected relations.

Original entry on oeis.org

1, 665, 106819, 10365005, 805351531, 56294206205, 3735873535339, 241600284318365, 15423235216318411, 978180744322139645, 61834480769377286059, 3902270609960140639325, 246057483524862034206091, 15508484277325946034039485, 977254123876968508188975979
Offset: 1

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Author

Goran Kilibarda and Vladeta Jovovic, Apr 14 2004

Keywords

Crossrefs

Programs

  • Mathematica
    Table[63^n-6*32^n-15*18^n+30*17^n-10*14^n+120*11^n-120*10^n+30*9^n-270*8^n+360*7^n-120*6^n, {n,1,25}] (* G. C. Greubel, Oct 06 2017 *)
    CoefficientList[Series[x (96368590080x^9+27682953984x^8-13185435000x^7+774468980x^6+ 143028190x^5-19071533x^4+626800x^3+6970x^2-470x-1)/((6x-1)(7x-1)(8x-1)(9x-1)(10x-1)(11x-1)(14x-1)(17x-1)(18x-1)(32x-1)(63x-1)),{x,0,20}],x] (* or *) LinearRecurrence[{195,-15886,726290,-20952193,403792115,-5336718048,48588590600,-299693200656,1195947048240,-2785165036416,2872859996160},{0,1,665,106819,10365005,805351531,56294206205,3735873535339,241600284318365,15423235216318411,978180744322139645},20] (* Harvey P. Dale, Sep 23 2023 *)
  • PARI
    for(n=1,25, print1(63^n-6*32^n-15*18^n+30*17^n-10*14^n+120*11^n-120*10^n+30*9^n-270*8^n+360*7^n-120*6^n, ", ")) \\ G. C. Greubel, Oct 06 2017

Formula

a(n) = 63^n - 6*32^n - 15*18^n + 30*17^n - 10*14^n + 120*11^n - 120*10^n + 30*9^n - 270*8^n + 360*7^n - 120*6^n.
G.f.: x*(96368590080*x^9 + 27682953984*x^8 - 13185435000*x^7 + 774468980*x^6 + 143028190*x^5 - 19071533*x^4 + 626800*x^3 + 6970*x^2 - 470*x - 1) / ((6*x -1)*(7*x -1)*(8*x -1)*(9*x -1)*(10*x -1)*(11*x -1)*(14*x -1)*(17*x -1)*(18*x -1)*(32*x -1)*(63*x -1)). - Colin Barker, Jul 07 2013

A114936 Number of connected (4,n)-hypergraphs (without empty edges).

Original entry on oeis.org

0, 1, 10, 135, 1992, 30166, 458885, 6965225, 105358102, 1588998756, 23915093535, 359444209015, 5397938190512, 81022969645346, 1215801458118985, 18240857019892005, 273644796626023722, 4104936328561231936
Offset: 0

Views

Author

Goran Kilibarda and Vladeta Jovovic, Jan 08 2006

Keywords

Crossrefs

Programs

  • Mathematica
    With[{nmax = 50}, CoefficientList[Series[(1/4!)*(Exp[15*x] - 4*Exp[8*x] + 6*Exp[7*x] - 3*Exp[6*x] + 12*Exp[5*x] - 24*Exp[4*x] + 23*Exp[3*x] - 11*Exp[2*x] + 6*Exp[x] - 6), {x, 0, nmax}], x] Range[0, nmax]!] (* G. C. Greubel, Oct 07 2017 *)
  • PARI
    x='x+O('x^50); concat([0], Vec(serlaplace((1/4!)*(exp(15*x) - 4*exp(8*x) + 6*exp(7*x) - 3*exp(6*x) + 12*exp(5*x) - 24*exp(4*x) + 23*exp(3*x) - 11*exp(2*x) + 6*exp(x) - 6)))) \\ G. C. Greubel, Oct 07 2017

Formula

E.g.f.: (1/4!)*(exp(15*x) - 4*exp(8*x) + 6*exp(7*x) - 3*exp(6*x) + 12*exp(5*x) - 24*exp(4*x) + 23*exp(3*x) - 11*exp(2*x) + 6*exp(x) - 6).

A114935 Number of connected (3,n)-hypergraphs (without empty edges).

Original entry on oeis.org

0, 1, 6, 44, 332, 2476, 18136, 130824, 933372, 6610676, 46603616, 327603904, 2298933412, 16115938476, 112906938696, 790735321784, 5536710117452, 38763269947876, 271368229299376, 1899679393564464, 13298164198917492
Offset: 0

Views

Author

Goran Kilibarda and Vladeta Jovovic, Jan 08 2006

Keywords

Crossrefs

Programs

  • Mathematica
    With[{nmax = 50}, CoefficientList[Series[(1/3!)*(Exp[7*x] - 3*Exp[4*x] + 5*Exp[3*x] - 3*Exp[2*x] + 2*Exp[x] - 2), {x, 0, nmax}], x] Range[0, nmax]!] (* G. C. Greubel, Oct 07 2017 *)
  • PARI
    x='x+O('x^50); concat([0], Vec(serlaplace((1/3!)*(exp(7*x) -3*exp(4*x) +5*exp(3*x) -3*exp(2*x) +2*exp(x) - 2)))) \\ G. C. Greubel, Oct 07 2017

Formula

E.g.f.: (1/3!)*(exp(7*x) -3*exp(4*x) +5*exp(3*x) -3*exp(2*x) +2*exp(x) - 2).

A114937 Number of connected (5,n)-hypergraphs (without empty edges).

Original entry on oeis.org

0, 1, 15, 336, 8880, 254596, 7606446, 231899522, 7137539256, 220623286632, 6831984816402, 211719998195278, 6562887569336652, 203453536535818388, 6307290799931347878, 195532244201392935354, 6061637498660735815968
Offset: 0

Views

Author

Goran Kilibarda and Vladeta Jovovic, Jan 08 2006

Keywords

Crossrefs

Formula

E.g.f.: (1/5!)*(exp(31*x) - 5*exp(16*x) + 10*exp(15*x) - 10*exp(10*x) + 20*exp(9*x) - 40*exp(8*x) + 65*exp(7*x) - 90*exp(6*x) + 144*exp(5*x) - 165*exp(4*x) + 120*exp(3*x) - 50*exp(2*x) + 24*exp(x) - 24).

A114934 Number of connected (5,n)-hypergraphs (without empty edges and without multiple edges).

Original entry on oeis.org

0, 0, 0, 21, 2773, 148365, 5878391, 204819447, 6721694469, 214306917321, 6736603947907, 210284186632443, 6541309609120385, 203129541349695597, 6302428271530970943, 195459285517696665759, 6060542952694406463421
Offset: 0

Views

Author

Goran Kilibarda and Vladeta Jovovic, Jan 08 2006

Keywords

Crossrefs

Programs

  • Mathematica
    With[{nmax = 50}, CoefficientList[Series[(1/5!)*(Exp[31*x] - 5*Exp[16*x] - 10*Exp[15*x] - 10*Exp[10*x] + 20*Exp[9*x] + 40*Exp[8*x] + 65*Exp[7*x] - 30*Exp[6*x] - 96*Exp[5*x] - 45*Exp[4*x] + 20*Exp[3*x] + 50*Exp[2*x] + 24*Exp[x] - 24), {x, 0, nmax}], x] Range[0, nmax]!] (* G. C. Greubel, Oct 07 2017 *)
  • PARI
    x='x+O('x^50); concat([0,0,0], Vec(serlaplace((1/5!)*(exp(31*x) - 5*exp(16*x) - 10*exp(15*x) - 10*exp(10*x) + 20*exp(9*x) + 40*exp(8*x) + 65*exp(7*x) - 30*exp(6*x) - 96*exp(5*x) - 45*exp(4*x) + 20*exp(3*x) + 50*exp(2*x) + 24*exp(x) - 24)))) \\ G. C. Greubel, Oct 07 2017

Formula

E.g.f.: (1/5!)*(exp(31*x) - 5*exp(16*x) - 10*exp(15*x) - 10*exp(10*x) + 20*exp(9*x) + 40*exp(8*x) + 65*exp(7*x) - 30*exp(6*x) - 96*exp(5*x) - 45*exp(4*x) + 20*exp(3*x) + 50*exp(2*x) + 24*exp(x) - 24).

A114933 Number of connected (4,n)-hypergraphs (without empty edges and without multiple edges).

Original entry on oeis.org

0, 0, 0, 32, 1094, 23055, 405475, 6575842, 102567444, 1569195485, 23775369725, 358461659952, 5391042181294, 80974624209115, 1215462744452775, 18238484835400862, 273628186560143144, 4104820038944901945
Offset: 0

Views

Author

Goran Kilibarda and Vladeta Jovovic, Jan 08 2006

Keywords

Crossrefs

Programs

  • Mathematica
    With[{nmax = 50}, CoefficientList[Series[(1/4!)*(Exp[15*x] - 4*Exp[8*x] - 6*Exp[7*x] - 3*Exp[6*x] + 12*Exp[5*x] + 12*Exp[4*x] - Exp[3*x] - 11*Exp[2*x] - 6*Exp[x] + 6), {x, 0, nmax}], x] Range[0, nmax]!] (* G. C. Greubel, Oct 07 2017 *)
  • PARI
    x='x+O('x^50); concat([0,0,0], Vec(serlaplace((1/4!)*(exp(15*x)-4*exp(8*x)-6*exp(7*x)-3*exp(6*x)+12*exp(5*x)+12*exp(4*x)-exp(3*x)-11*exp(2*x)-6*exp(x)+6)))) \\ G. C. Greubel, Oct 07 2017

Formula

E.g.f.: (1/4!)*(exp(15*x) - 4*exp(8*x) - 6*exp(7*x) - 3*exp(6*x) + 12*exp(5*x) + 12*exp(4*x) - exp(3*x) - 11*exp(2*x) - 6*exp(x) + 6).

A226658 T(n,k)=Number of nXk 0..4 arrays of sums of 2X2 subblocks of some (n+1)X(k+1) binary array.

Original entry on oeis.org

5, 19, 19, 65, 205, 65, 211, 1795, 1795, 211, 665, 14221, 36317, 14221, 665, 2059, 106819, 636331, 636331, 106819, 2059, 6305, 778765, 10365005, 23679901, 10365005, 778765, 6305, 19171, 5581315, 162470155, 805351531, 805351531, 162470155
Offset: 1

Views

Author

R. H. Hardin Jun 14 2013

Keywords

Comments

Table starts
......5.........19...........65............211.............665............2059
.....19........205.........1795..........14221..........106819..........778765
.....65.......1795........36317.........636331........10365005.......162470155
....211......14221.......636331.......23679901.......805351531.....26175881341
....665.....106819.....10365005......805351531.....56294206205...3735873535339
...2059.....778765....162470155....26175881341...3735873535339.502757743028605
...6305....5581315...2495037197...831358677451.241600284318365
..19171...39606541..37898120011.26094426008221
..58025..279447619.572284920845
.175099.1965098125
.527345

Examples

			Some solutions for n=3 k=4
..1..1..1..0....0..1..1..1....0..1..1..0....1..0..1..1....1..0..2..3
..3..1..1..2....1..1..2..1....1..2..2..2....1..2..3..2....1..2..2..1
..3..2..2..3....3..1..2..3....2..1..2..3....2..3..2..1....3..3..1..0
		

Crossrefs

Diagonal is A005333(n+1)
Staircase diagonal is A123281(n-3)
Column 1 is A001047(n+1)
Column 2 is A002501(n+1)
Column 3 is A002502(n+1)
Column 4 is A093732(n+1)
Column 5 is A093733(n+1)

A114932 Number of connected (3,n)-hypergraphs (without empty edges and without multiple edges).

Original entry on oeis.org

0, 0, 1, 25, 267, 2265, 17471, 128765, 927067, 6591505, 46545591, 327428805, 2298406067, 16114352345, 112902172111, 790721005645, 5536667136267, 38763140938785, 271367842141031, 1899678231827285, 13298160713181667
Offset: 0

Views

Author

Goran Kilibarda and Vladeta Jovovic, Jan 08 2006

Keywords

Crossrefs

Programs

  • Mathematica
    With[{nmax = 50}, CoefficientList[Series[(1/3!)*(Exp[7*x] - 3*Exp[4*x] - Exp[3*x] + 3*Exp[2*x] + 2*Exp[x] - 2), {x, 0, nmax}], x] Range[0, nmax]!] (* G. C. Greubel, Oct 07 2017 *)
  • PARI
    x='x+O('x^50); concat([0,0], Vec(serlaplace((1/3!)*(exp(7*x)-3*exp(4*x)-exp(3*x)+3*exp(2*x)+2*exp(x)-2)))) \\ G. C. Greubel, Oct 07 2017

Formula

E.g.f.: (1/3!)*(exp(7*x)-3*exp(4*x)-exp(3*x)+3*exp(2*x)+2*exp(x)-2).
Showing 1-10 of 14 results. Next