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 1-4 of 4 results.

A006300 Number of rooted maps with n edges on torus.

Original entry on oeis.org

1, 20, 307, 4280, 56914, 736568, 9370183, 117822512, 1469283166, 18210135416, 224636864830, 2760899996816, 33833099832484, 413610917006000, 5046403030066927, 61468359153954656, 747672504476150374, 9083423595292949240, 110239596847544663002, 1336700736225591436496, 16195256987701502444284
Offset: 2

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Author

Keywords

References

  • E. R. Canfield, Calculating the number of rooted maps on a surface, Congr. Numerantium, 76 (1990), 21-34.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • T. R. S. Walsh, Combinatorial Enumeration of Non-Planar Maps. Ph.D. Dissertation, Univ. of Toronto, 1971.

Crossrefs

Column k=1 of A238396.
Rooted maps with n edges of genus g for 0 <= g <= 10: A000168, this sequence, A006301, A104742, A215402, A238355, A238356, A238357, A238358, A238359, A238360.

Programs

  • Maple
    R:=sqrt(1-12*x): seq(coeff(convert(series((R-1)^2/(12*R^2*(R+2)),x,50),polynom),x,n),n=2..25); (Pab Ter)
  • Mathematica
    Drop[With[{c=Sqrt[1-12x]},CoefficientList[Series[(c-1)^2/(12c^2 (c+2)), {x,0,30}],x]],2] (* Harvey P. Dale, Jun 14 2011 *)
  • PARI
    A005159_ser(N) = my(x='x+O('x^(N+1))); (1 - sqrt(1-12*x))/(6*x);
    A006300_ser(N) = my(y = A005159_ser(N+1)); y*(y-1)^2/(3*(y-2)^2*(y+2));
    Vec(A006300_ser(21)) \\ Gheorghe Coserea, Jun 02 2017

Formula

G.f.: (R-1)^2/(12*R^2*(R+2)) where R=sqrt(1-12*x); a(n) is asymptotic to 12^n/24. - Pab Ter (pabrlos2(AT)yahoo.com), Nov 07 2005
a(n) = Sum_{k=0..n-2} 2^(n-3-k)*(3^(n-1)-3^k)*binomial(n+k,k). - Ruperto Corso, Dec 18 2011
D-finite with recurrence: n*a(n) +22*(-n+1)*a(n-1) +4*(22*n-65)*a(n-2) +96*(5*n-4)*a(n-3) +576*(-2*n+7)*a(n-4)=0. - R. J. Mathar, Feb 20 2020

Extensions

Bender et al. give 20 terms.
More terms from Pab Ter (pabrlos2(AT)yahoo.com), Nov 07 2005
More terms from Joerg Arndt, Feb 26 2014

A267180 Triangle read by rows: T(n,k) = number of rooted maps with n edges on a nonorientable surface of genus k (1 <= k <= n).

Original entry on oeis.org

1, 10, 4, 98, 84, 41, 982, 1340, 1380, 488, 10062, 19280, 31225, 23320, 8229, 105024, 263284, 592824, 696912, 516958, 164892, 1112757, 3486224, 10185056, 16662492, 19381145, 12980716, 4016613, 11934910, 45247084, 164037704, 348539072, 562395292, 590136856, 382630152, 112818960
Offset: 1

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Author

N. J. A. Sloane, Jan 16 2016

Keywords

Examples

			Triangle begins:
1,
10,4,
98,84,41,
982,1340,1380,488,
10062,19280,31225,23320,8229,
105024,263284,592824,696912,516958,164892,
1112757,3486224,10185056,16662492,19381145,12980716,4016613,
11934910,45247084,164037704,348539072,562395292,590136856,382630152,112818960
...
		

References

  • David M. Jackson and Terry I. Visentin, An Atlas of the Smaller Maps in Orientable and Nonorientable Surfaces, Chapman & Hall/CRC, circa 2000. See page 227.

Crossrefs

See A238396 for analog for orientable surfaces.
Columns give A007137, A006344.
Cf. A380235 (unrooted).

A316598 a(n) is the number of rooted quadrangulations of the projective plane with n vertices.

Original entry on oeis.org

5, 38, 331, 3098, 30330, 306276, 3163737, 33252050, 354312946, 3817498004, 41510761346, 454882507468, 5017662052868, 55664182358808, 620592559670979, 6949200032479746, 78117065527443654, 881170275583541004, 9970663315885385502, 113137928354523348300
Offset: 1

Views

Author

Gheorghe Coserea, Jul 08 2018

Keywords

Crossrefs

Programs

  • Mathematica
    (-6*x + 3*Sqrt[1-12*x] - 2*Sqrt[-36*x + 6*Sqrt[1-12*x] + 3] + 3)/(6*x^2) + O[x]^20 // CoefficientList[#, x]& (* Jean-François Alcover, Feb 24 2019 *)
  • PARI
    seq(N) = {
      my(x='x + O('x^(N+2)), c=(1-sqrt(1-12*x))/(6*x));
      Vec((1 - x - 3*x*c - sqrt(1 - 4*x - 4*x*c))/x);
    };
    seq(20)
    \\ test: y='x*Ser(seq(300), 'x); 0 == 3*x^3*y^4 + (12*x^3 - 6*x^2)*y^3 + (18*x^3 + 24*x^2 + x)*y^2 + (12*x^3 + 66*x^2 + 8*x - 2)*y + (3*x^3 + 36*x^2 + 10*x)

Formula

G.f. A(x) = (1-x-3*x*c - sqrt(1-4*x-4*x*c))/x, where c=(1-sqrt(1-12*x))/(6*x). (see eqn. (117) in Garoufalidis link)
G.f. y=A(x) satisfies:
0 = 3*x^3*y^4 + 6*x^2*(2*x - 1)*y^3 + x*(18*x^2 + 24*x + 1)*y^2 + 2*(6*x^3 + 33*x^2 + 4*x - 1)*y + x*(3*x^2 + 36*x + 10).
0 = 13*x*(4*x + 1)*(12*x - 1)^3*y''''' + (36864*x^4 + 3840*x^3 + 8832*x^2 + 1556*x - 65)*(12*x - 1)^2*y'''' + 16*(248832*x^4 - 5184*x^3 + 29799*x^2 + 2418*x - 259)*(12*x - 1)*y''' + 72*(1382400*x^4 - 201600*x^3 + 144312*x^2 - 4157*x - 492)*y'' + 144*(276480*x^3 - 51840*x^2 + 31488*x - 979)*y' + 165888*y.
0 = x*(4*x + 1)*(48*x^2 - 6*x + 1)*(12*x - 1)^3*y'''' + 2*(10368*x^4 + 12*x^2 + 47*x - 2)*(12*x - 1)^2*y''' + 6*(86400*x^4 - 10800*x^3 + 2472*x^2 + 132*x - 19)*(12*x - 1)*y'' + (2488320*x^4 - 622080*x^3 + 186192*x^2 - 10728*x - 144)*y' + (10368*x - 648)*y.
a(n) ~ 2^(2*n + 1/2) * 3^(n + 1/2)/ (Gamma(3/4) * n^(5/4)) * (1 - sqrt(3) * Gamma(3/4) / (sqrt(2*Pi) * n^(1/4))). - Vaclav Kotesovec, Oct 04 2019

A316698 a(n) is the number of rooted 2-connected triangular maps on the projective plane with n vertices.

Original entry on oeis.org

0, 0, 1, 18, 261, 3539, 46695, 608526, 7884661, 101905839, 1316047599, 16998339587, 219699143367, 2842235616645, 36809980380883, 477280717428102, 6195737611180053, 80522713890559319, 1047702563499718623, 13646946767000964471, 177947654115176898479
Offset: 1

Views

Author

Gheorghe Coserea, Jul 10 2018

Keywords

Crossrefs

Programs

  • PARI
    seq(N) = {
      my(x = 'x + O('x^(N+1)), r=serreverse(x*(1-2*x)^2),
         v = Vec(subst((1-sqrt((1-6*x)/(1-2*x)))/(2*x)-1/(1-3*x), 'x, r)));
      concat([0,0], v);
    };
    seq(21)

Formula

G.f. A(x) = (1 - sqrt((1-6*r)/(1-2*r)))/(2*r) - 1/(1-3*r), where r(x) satisfies x = r*(1-2*r)^2, with r(0)=0. (see (1.1) in Gao link)
G.f. y=A(x) satisfies: 0 = (729*x^2 - 54*x + 1)*y^6 + (-567*x^2 + 48*x - 1)*y^5 + (4617*x^3 - 486*x^2 + 12*x)*y^4 + (-14310*x^4 + 1772*x^3 - 54*x^2)*y^3 + (-672*x^4 + 50*x^3)*y^2 + (126*x^5 - 36*x^4 + 2*x^3)*y - 2*x^6.
Recurrence: (n-1)*n*(2*n - 3)*(4*n - 9)*(4*n - 3)*(972*n^7 - 1944*n^6 - 169443*n^5 + 1865607*n^4 - 8817457*n^3 + 21764795*n^2 - 27508222*n + 14065464)*a(n) = 3*(n-1)*(699840*n^11 - 5598720*n^10 - 107581284*n^9 + 2120974416*n^8 - 16716827583*n^7 + 77044659801*n^6 - 229110154570*n^5 + 453176543549*n^4 - 592757452327*n^3 + 491840891214*n^2 - 233773288056*n + 48250762560)*a(n-1) - 9*(5668704*n^12 - 61410960*n^11 - 770480100*n^10 + 20379495348*n^9 - 192680893665*n^8 + 1066797111051*n^7 - 3886131103119*n^6 + 9712411159089*n^5 - 16796662782944*n^4 + 19765806847064*n^3 - 15086450010036*n^2 + 6716653116768*n - 1318624045200)*a(n-2) + 486*(3*n - 11)*(3*n - 10)*(122472*n^10 - 717336*n^9 - 21548106*n^8 + 353617272*n^7 - 2470176720*n^6 + 10020300957*n^5 - 25599297354*n^4 + 41773597853*n^3 - 42167708852*n^2 + 23887121874*n - 5766718860)*a(n-3) - 26244*(n-4)*(3*n - 14)*(3*n - 13)*(3*n - 11)*(3*n - 10)*(972*n^7 + 4860*n^6 - 160695*n^5 + 1023252*n^4 - 3054319*n^3 + 4802888*n^2 - 3820650*n + 1199772)*a(n-4). - Vaclav Kotesovec, Jul 11 2018
a(n) ~ (27/2)^n * (1/(2*3^(7/4)*Gamma(3/4)) - 10/(27*sqrt(3*Pi)*n^(1/4)) + sqrt(2)*Gamma(3/4) / (3^(9/4)*Pi*sqrt(n))) / n^(5/4) [main asymptotic term by Gao, 1991]. - Vaclav Kotesovec, Jul 11 2018
Showing 1-4 of 4 results.