A380235
Triangle read by rows: T(n,k) is the number of n edge non-orientable genus k maps.
Original entry on oeis.org
1, 4, 2, 19, 16, 8, 106, 137, 128, 47, 709, 1254, 1890, 1372, 473, 5356, 12597, 27036, 31007, 22556, 7190, 44558, 133518, 379491, 611322, 704066, 469632, 144904, 397146, 1464725, 5229092, 11017122, 17691240, 18521632, 11990766, 3534490, 3716039, 16373700, 70805740, 186044902, 387965547, 563764626, 571333104, 352456980, 100895667
Offset: 1
Triangle begins:
1;
4, 2;
19, 16, 8;
106, 137, 128, 47;
709, 1254, 1890, 1372, 473;
5356, 12597, 27036, 31007, 22556, 7190;
44558, 133518, 379491, 611322, 704066, 469632, 144904;
...
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
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, ...,
...
- 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.
Columns k for 0<=k<=10 are:
A000168,
A006300,
A006301,
A104742,
A215402,
A238355,
A238356,
A238357,
A238358,
A238359,
A238360.
See
A267180 for nonorientable analog.
The triangle without the zeros is
A269919.
-
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 *)
-
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 */
A007137
Number of rooted maps with n edges on the projective plane.
Original entry on oeis.org
1, 10, 98, 982, 10062, 105024, 1112757, 11934910, 129307100, 1412855500, 15548498902, 172168201088, 1916619748084, 21436209373224, 240741065193282, 2713584138389838, 30687358107371442, 348061628432108352
Offset: 1
- E. R. Canfield, Calculating the number of rooted maps on a surface, Congr. Numerantium, 76 (1990), 21-34.
- 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.
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
- T. D. Noe, Table of n, a(n) for n = 1..100
- E. A. Bender, E. R. Canfield and R. W. Robinson, The enumeration of maps on the torus and the projective plane, Canad. Math. Bull., 31 (1988), 257-271; see p. 270.
- Guillaume Chapuy, Maciej Dołęga, A bijection for rooted maps on general surfaces, arXiv:1501.06942 [math.CO], 2016; see corollary 4.5.
- Valery A. Liskovets, A reductive technique for enumerating non-isomorphic planar maps, Discrete Math. 156 (1996), no. 1-3, 197--217. MR1405018 (97f:05087). - _N. J. A. Sloane_, Jun 03 2012
-
R:=sqrt(1-12*x): seq(coeff(convert(series(((2*R+1)/3-sqrt(R*(R+2)/3))/(2*x),x,50),polynom),x,n),n=1..25); # Pab Ter, Nov 07 2005
-
With[{r=Sqrt[1-12x]},Rest[CoefficientList[Series[((2r+1)/3-Sqrt[r (r+2)/3])/ (2x),{x,0,20}],x]]](* Harvey P. Dale, Mar 02 2018 *)
-
seq(N) = {
my(x = 'x + O('x^(N+2)), r=sqrt(1-12*x));
Vec(((2*r+1)/3 - sqrt(r*(r+2)/3))/(2*x));
};
seq(18)
\\ test: y = 'x*Ser(seq(300),'x); 0 == 9*x^3*y^4 - 6*x^2*y^3 + 2*x*(21*x - 1)*y^2 + (10*x - 1)*y + x
\\ Gheorghe Coserea, Jul 07 2018
-
b(n) = sum(k=0, n\2, n!/(k!^2 * (n - 2*k)!)); \\ A002426
a(n) = 2*sum(k=0, n-1, binomial(2*n, k) * 3^k * b(n-k))/(n+1);
vector(18, n, a(n)) \\ Gheorghe Coserea, Dec 26 2018
Reference gives 20 terms
Description corrected May 15 1997, thanks to Jean-Francois Beraud
More terms from Pab Ter (pabrlos2(AT)yahoo.com), Nov 07 2005
A006344
Number of rooted maps with n edges on Klein bottle.
Original entry on oeis.org
4, 84, 1340, 19280, 263284, 3486224, 45247084, 579150012, 7338291224, 92272957568, 1153361204996, 14348020042512, 177803262186064, 2196338193610064, 27057921450352204, 332583930387073712
Offset: 2
Jean-Francois Beraud (beraud(AT)univ-mlv.fr)
- 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.
A118450
Number of rooted n-edge one-vertex one-face maps on a non-orientable surface (of genus n).
Original entry on oeis.org
1, 4, 41, 488, 8229, 164892, 4016613, 112818960
Offset: 1
- E. R. Canfield, Calculating the number of rooted maps on a surface, Congr. Numerantium, 76 (1990), 21-34.
- D. M. Jackson and T. I. Visentin, An atlas of the smaller maps in orientable and nonorientable surfaces. CRC Press, Boca Raton, 2001.
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