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.

Previous Showing 11-17 of 17 results.

A269924 Triangle read by rows: T(n,f) is the number of rooted maps with n edges and f faces on an orientable surface of genus 4.

Original entry on oeis.org

225225, 12317877, 12317877, 351683046, 792534015, 351683046, 7034538511, 26225260226, 26225260226, 7034538511, 111159740692, 600398249550, 993494827480, 600398249550, 111159740692, 1480593013900, 10743797911132, 25766235457300, 25766235457300, 10743797911132, 1480593013900, 17302190625720, 160576594766588, 517592962672296, 750260619502310, 517592962672296, 160576594766588, 17302190625720
Offset: 8

Views

Author

Gheorghe Coserea, Mar 15 2016

Keywords

Comments

Row n contains n-7 terms.

Examples

			Triangle starts:
n\f  [1]           [2]           [3]           [4]
[8]  225225;
[9]  12317877,     12317877;
[10] 351683046,    792534015,    351683046;
[11] 7034538511,   26225260226,  26225260226,  7034538511;
[12] ...
		

Crossrefs

Columns f=1-10 give: A288271 f=1, A288272 f=2, A288273 f=3, A288274 f=4, A288275 f=5, A288276 f=6, A288277 f=7, A288278 f=8, A288279 f=9, A288280 f=10.
Row sums give A215402 (column 4 of A269919).

Programs

  • Mathematica
    Q[0, 1, 0] = 1; Q[n_, f_, g_] /; n<0 || f<0 || g<0 = 0;
    Q[n_, f_, g_] := Q[n, f, g] = 6/(n+1)((2n-1)/3 Q[n-1, f, g] + (2n-1)/3 Q[n - 1, f-1, g] + (2n-3)(2n-2)(2n-1)/12 Q[n-2, f, g-1] + 1/2 Sum[l = n-k; Sum[v = f-u; Sum[j = g-i; Boole[l >= 1 && v >= 1 && j >= 0] (2k-1) (2l-1) Q[k-1, u, i] Q[l-1, v, j], {i, 0, g}], {u, 1, f}], {k, 1, n}]);
    Table[Q[n, f, 4], {n, 8, 14}, {f, 1, n-7}] // Flatten (* Jean-François Alcover, Aug 10 2018 *)
  • PARI
    N = 14; G = 4; gmax(n) = min(n\2, G);
    Q = matrix(N + 1, N + 1);
    Qget(n, g) = { if (g < 0 || g > n/2, 0, Q[n+1, g+1]) };
    Qset(n, g, v) = { Q[n+1, g+1] = v };
    Quadric({x=1}) = {
      Qset(0, 0, x);
      for (n = 1, length(Q)-1, for (g = 0, gmax(n),
        my(t1 = (1+x)*(2*n-1)/3 * Qget(n-1, g),
           t2 = (2*n-3)*(2*n-2)*(2*n-1)/12 * Qget(n-2, g-1),
           t3 = 1/2 * sum(k = 1, n-1, sum(i = 0, g,
           (2*k-1) * (2*(n-k)-1) * Qget(k-1, i) * Qget(n-k-1, g-i))));
        Qset(n, g, (t1 + t2 + t3) * 6/(n+1))));
    };
    Quadric('x);
    concat(apply(p->Vecrev(p/'x), vector(N+1 - 2*G, n, Qget(n-1 + 2*G, G))))

A269925 Triangle read by rows: T(n,f) is the number of rooted maps with n edges and f faces on an orientable surface of genus 5.

Original entry on oeis.org

59520825, 4304016990, 4304016990, 158959754226, 354949166565, 158959754226, 4034735959800, 14805457339920, 14805457339920, 4034735959800, 79553497760100, 420797306522502, 691650582088536, 420797306522502, 79553497760100, 1302772718028600, 9220982517965400, 21853758736216200, 21853758736216200, 9220982517965400, 1302772718028600
Offset: 10

Views

Author

Gheorghe Coserea, Mar 15 2016

Keywords

Comments

Row n contains n-9 terms.

Examples

			Triangle starts:
n\f  [1]             [2]             [3]             [4]
[10] 59520825;
[11] 4304016990,     4304016990;
[12] 15895975422,    354949166565,   158959754226;
[13] 4034735959800,  14805457339920, 14805457339920, 4034735959800;
[14] ...
		

Crossrefs

Rooted maps of genus 5 with n edges and f faces for 1<=f<=10: A288281 f=1, A288282 f=2, A288283 f=3, A288284 f=4, A288285 f=5, A288286 f=6, A288287 f=7, A288288 f=8, A288289 f=9, A288290 f=10.
Row sums give A238355 (column 5 of A269919).

Programs

  • Mathematica
    Q[0, 1, 0] = 1; Q[n_, f_, g_] /; n<0 || f<0 || g<0 = 0;
    Q[n_, f_, g_] := Q[n, f, g] = 6/(n+1)((2n-1)/3 Q[n-1, f, g] + (2n-1)/3 Q[n - 1, f-1, g] + (2n-3)(2n-2)(2n-1)/12 Q[n-2, f, g-1] + 1/2 Sum[l = n-k; Sum[v = f-u; Sum[j = g-i; Boole[l >= 1 && v >= 1 && j >= 0] (2k-1)(2l-1) Q[k-1, u, i] Q[l-1, v, j], {i, 0, g}], {u, 1, f}], {k, 1, n}]);
    Table[Q[n, f, 5], {n, 10, 15}, {f, 1, n-9}] // Flatten (* Jean-François Alcover, Aug 10 2018 *)
  • PARI
    N = 15; G = 5; gmax(n) = min(n\2, G);
    Q = matrix(N + 1, N + 1);
    Qget(n, g) = { if (g < 0 || g > n/2, 0, Q[n+1, g+1]) };
    Qset(n, g, v) = { Q[n+1, g+1] = v };
    Quadric({x=1}) = {
      Qset(0, 0, x);
      for (n = 1, length(Q)-1, for (g = 0, gmax(n),
        my(t1 = (1+x)*(2*n-1)/3 * Qget(n-1, g),
           t2 = (2*n-3)*(2*n-2)*(2*n-1)/12 * Qget(n-2, g-1),
           t3 = 1/2 * sum(k = 1, n-1, sum(i = 0, g,
           (2*k-1) * (2*(n-k)-1) * Qget(k-1, i) * Qget(n-k-1, g-i))));
        Qset(n, g, (t1 + t2 + t3) * 6/(n+1))));
    };
    Quadric('x);
    concat(apply(p->Vecrev(p/'x), vector(N+1 - 2*G, n, Qget(n-1 + 2*G, G))))

A379438 Triangle read by rows: T(n,k) is the number of sensed combinatorial maps with n edges and genus k, 0 <= k <= floor(n/2).

Original entry on oeis.org

1, 2, 4, 1, 14, 6, 57, 46, 4, 312, 452, 106, 2071, 4852, 2382, 131, 15030, 52972, 46680, 8158, 117735, 587047, 830848, 313611, 14118, 967850, 6550808, 13804864, 9326858, 1369446, 8268816, 73483256, 218353000, 236095958, 74803564, 2976853, 72833730, 827801468, 3328822880, 5345316004, 3023693380, 391288854
Offset: 0

Views

Author

Andrew Howroyd, Jan 16 2025

Keywords

Examples

			Triangle begins:
  n\k     [0]      [1]       [2]      [3]      [4]
  [0]      1;
  [1]      2;
  [2]      4,       1;
  [3]     14,       6;
  [4]     57,      46,        4;
  [5]    312,     452,      106;
  [6]   2071,    4852,     2382,     131;
  [7]  15030,   52972,    46680,    8158;
  [8] 117735,  587047,   830848,  313611,   14118;
  [9] 967850, 6550808, 13804864, 9326858, 1369446;
  ...
		

Crossrefs

Row sums are A170946.
Cf. A269919 (rooted), A379439 (unsensed), A380234 (achiral), A380235.

A379439 Triangle read by rows: T(n,k) is the number of unsensed combinatorial maps with n edges and genus k, 0 <= k <= floor(n/2).

Original entry on oeis.org

1, 2, 4, 1, 14, 6, 52, 40, 4, 248, 320, 76, 1416, 2946, 1395, 82, 9172, 29364, 24950, 4348, 66366, 309558, 427336, 160050, 7258, 518868, 3365108, 6987100, 4696504, 688976, 4301350, 37246245, 109761827, 118353618, 37466297, 1491629, 37230364, 416751008, 1668376886, 2675297588, 1512650776, 195728778
Offset: 0

Views

Author

Andrew Howroyd, Jan 16 2025

Keywords

Examples

			Triangle begins:
  n\k     [0]      [1]      [2]      [3]     [4]
  [0]      1;
  [1]      2;
  [2]      4,       1;
  [3]     14,       6;
  [4]     52,      40,       4;
  [5]    248,     320,      76;
  [6]   1416,    2946,    1395,      82;
  [7]   9172,   29364,   24950,    4348;
  [8]  66366,  309558,  427336,  160050,   7258;
  [9] 518868, 3365108, 6987100, 4696504, 688976;
		

Crossrefs

Row sums are A214816.
Cf. A269919 (rooted), A379438 (sensed), A380234 (achiral), A380235.

Formula

T(n,k) = (A379438(n,k) + A380234(n,k))/2.

A269923 Triangle read by rows: T(n,f) is the number of rooted maps with n edges and f faces on an orientable surface of genus 3.

Original entry on oeis.org

1485, 56628, 56628, 1169740, 2668750, 1169740, 17454580, 66449432, 66449432, 17454580, 211083730, 1171704435, 1955808460, 1171704435, 211083730, 2198596400, 16476937840, 40121261136, 40121261136, 16476937840, 2198596400, 20465052608, 196924458720, 647739636160
Offset: 6

Views

Author

Gheorghe Coserea, Mar 15 2016

Keywords

Comments

Row n contains n-5 terms.

Examples

			Triangle starts:
n\f  [1]          [2]          [3]          [4]          [5]
[6]  1485;
[7]  56628,       56628;
[8]  1169740,     2668750,     1169740;
[9]  17454580,    66449432,    66449432,    17454580;
[10] 211083730,   1171704435,  1955808460,  1171704435,  211083730;
[11] ...
		

Crossrefs

Columns f=1-10 give: A288075 f=1, A288076 f=2, A288077 f=3, A288078 f=4, A288079 f=5, A288080 f=6, A288081 f=7, A288262 f=8, A288263 f=9, A288264 f=10.
Row sums give A104742 (column 3 of A269919).

Programs

  • Mathematica
    Q[0, 1, 0] = 1; Q[n_, f_, g_] /; n<0 || f<0 || g<0 = 0;
    Q[n_, f_, g_] := Q[n, f, g] = 6/(n+1)((2n-1)/3 Q[n-1, f, g] + (2n-1)/3 Q[n - 1, f-1, g] + (2n-3)(2n-2)(2n-1)/12 Q[n-2, f, g-1] + 1/2 Sum[l = n-k; Sum[v = f-u; Sum[j = g-i; Boole[l >= 1 && v >= 1 && j >= 0] (2k-1) (2l-1) Q[k-1, u, i] Q[l-1, v, j], {i, 0, g}], {u, 1, f}], {k, 1, n}]);
    Table[Q[n, f, 3], {n, 6, 12}, {f, 1, n-5}] // Flatten (* Jean-François Alcover, Aug 10 2018 *)
  • PARI
    N = 12; G = 3; gmax(n) = min(n\2, G);
    Q = matrix(N + 1, N + 1);
    Qget(n, g) = { if (g < 0 || g > n/2, 0, Q[n+1, g+1]) };
    Qset(n, g, v) = { Q[n+1, g+1] = v };
    Quadric({x=1}) = {
      Qset(0, 0, x);
      for (n = 1, length(Q)-1, for (g = 0, gmax(n),
        my(t1 = (1+x)*(2*n-1)/3 * Qget(n-1, g),
           t2 = (2*n-3)*(2*n-2)*(2*n-1)/12 * Qget(n-2, g-1),
           t3 = 1/2 * sum(k = 1, n-1, sum(i = 0, g,
           (2*k-1) * (2*(n-k)-1) * Qget(k-1, i) * Qget(n-k-1, g-i))));
        Qset(n, g, (t1 + t2 + t3) * 6/(n+1))));
    };
    Quadric('x);
    concat(apply(p->Vecrev(p/'x), vector(N+1 - 2*G, n, Qget(n-1 + 2*G, G))))

A238396 Triangle T(n,k) read by rows: T(n,k) is the number of rooted genus-k maps with n edges, n>=0, 0<=k<=n.

Original entry on oeis.org

1, 2, 0, 9, 1, 0, 54, 20, 0, 0, 378, 307, 21, 0, 0, 2916, 4280, 966, 0, 0, 0, 24057, 56914, 27954, 1485, 0, 0, 0, 208494, 736568, 650076, 113256, 0, 0, 0, 0, 1876446, 9370183, 13271982, 5008230, 225225, 0, 0, 0, 0, 17399772, 117822512, 248371380, 167808024, 24635754, 0, 0, 0, 0, 0, 165297834, 1469283166, 4366441128, 4721384790, 1495900107, 59520825, 0
Offset: 0

Views

Author

Joerg Arndt, Feb 26 2014

Keywords

Examples

			Triangle starts:
00: 1,
01: 2, 0,
02: 9, 1, 0,
03: 54, 20, 0, 0,
04: 378, 307, 21, 0, 0,
05: 2916, 4280, 966, 0, 0, 0,
06: 24057, 56914, 27954, 1485, 0, 0, 0,
07: 208494, 736568, 650076, 113256, 0, 0, 0, 0,
08: 1876446, 9370183, 13271982, 5008230, 225225, 0, 0, 0, 0,
09: 17399772, 117822512, 248371380, 167808024, 24635754, 0, ...,
10: 165297834, 1469283166, 4366441128, 4721384790, 1495900107, 59520825, 0, ...,
11: 1602117468, 18210135416, 73231116024, 117593590752, 66519597474, 8608033980, 0, ...,
12: 15792300756, 224636864830, 1183803697278, 2675326679856, 2416610807964, 672868675017, 24325703325, 0, ...,
...
		

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

Sum of row n is A000698(n+1).
See A267180 for nonorientable analog.
The triangle without the zeros is A269919.

Programs

  • Mathematica
    T[0, 0] = 1; T[n_, g_] /; g < 0 || g > n/2 = 0; T[n_, g_] := T[n, g] = ((4n - 2)/3 T[n-1, g] + (2n-3)(2n-2)(2n-1)/12 T[n-2, g-1] + 1/2 Sum[(2k-1)(2(n - k)-1) T[k-1, i] T[n-k-1, g-i] , {k, 1, n-1}, {i, 0, g}])/((n+1)/6);
    Table[T[n, g], {n, 0, 10}, {g, 0, n}] // Flatten (* Jean-François Alcover, Jul 19 2018, after Gheorghe Coserea *)
  • PARI
    N=20;
    MEM=matrix(N+1,N+1, r,c, -1);  \\ for memoization
    Q(n,g)=
    {
        if (n<0,  return( (g<=0) ) ); \\ not given in paper
        if (g<0,  return( 0 ) ); \\ not given in paper
        if (n<=0, return( g==0 ) );  \\ as in paper
        my( m = MEM[n+1,g+1] );
        if ( m != -1,  return(m) );  \\ memoized value
        my( t=0 );
        t += (4*n-2)/3 * Q(n-1, g);
        t += (2*n-3)*(2*n-2)*(2*n-1)/12 * Q(n-2, g-1);
        my(l, j);
        t += 1/2*
            sum(k=1, n-1, l=n-k;  \\ l+k == n, both >= 1
                sum(i=0, g, j=g-i;  \\ i+j == g, both >= 0
                    (2*k-1)*(2*l-1) * Q(k-1, i) * Q(l-1, j)
                );
            );
        t *= 6/(n+1);
        MEM[n+1, g+1] = t;  \\ memoize
        return(t);
    }
    for (n=0, N, for (g=0, n, print1(Q(n, g),", "); );  print(); ); /* print triangle */

Formula

From Gheorghe Coserea, Mar 11 2016: (Start)
(n+1)/6 * T(n, g) = (4*n-2)/3 * T(n-1, g) + (2*n-3)*(2*n-2)*(2*n-1)/12 * T(n-2, g-1) + 1/2 * Sum_{k=1..n-1} Sum_{i=0..g} (2*k-1) * (2*(n-k)-1) * T(k-1, i) * T(n-k-1, g-i) for all n >= 1 and 0 <= g <= n/2, with the initial conditions T(0,0) = 1 and T(n,g) = 0 for g < 0 or g > n/2.
For column g, as n goes to infinity we have T(n,g) ~ t(g) * n^(5*(g-1)/2) * 12^n, where t(g) = (A269418(g)/A269419(g)) / (2^(g-2) * gamma((5*g-1)/2)) and gamma is the Gamma function.
(End)

A380622 Array read by antidiagonals: T(n,k) is the number of rooted k-regular combinatorial maps with n vertices, n >= 0, k >= 1.

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 3, 5, 1, 0, 1, 0, 24, 0, 1, 0, 1, 15, 189, 297, 60, 1, 0, 1, 0, 1695, 0, 4896, 0, 1, 0, 1, 105, 19305, 472200, 869400, 100278, 1105, 1, 0, 1, 0, 252000, 0, 242183775, 0, 2450304, 0, 1, 0, 1, 945, 3828825, 2465608950, 103694490900, 198147676875, 16482741030, 69533397, 27120, 1, 0
Offset: 0

Views

Author

Andrew Howroyd, Jan 29 2025

Keywords

Comments

The combinatorial maps considered are connected, unlabeled, may have loops and parallel edges and are of any orientable genus.

Examples

			Array begins:
============================================================
n\k | 1 2    3       4      5         6     7          8 ...
----+-------------------------------------------------------
  0 | 1 1    1       1      1         1     1          1 ...
  1 | 0 1    0       3      0        15     0        105 ...
  2 | 1 1    5      24    189      1695 19305     252000 ...
  3 | 0 1    0     297      0    472200     0 2465608950 ...
  4 | 0 1   60    4896 869400 242183775 ...
  5 | 0 1    0  100278      0 ...
  6 | 0 1 1105 2450304 ...
  7 | 0 1    0 ...
  ...
		

Crossrefs

Columns 2..6 are A000012, A062980 (with interspersed zeros), A292186, A380623 (with interspersed zeros), A380624.

Programs

  • PARI
    T(n,k)={my(A=O(x^(n*k+1)), g=serlaplace(serconvol(exp(x^k/k + A), exp(x^2/2 + A)))); polcoef(1 + x*deriv(g)/g, n*k)}

Formula

A380625(n) = Sum_{d|2*n} T(d,2*n/d).
Previous Showing 11-17 of 17 results.