Original entry on oeis.org
1, 6, 56, 640, 8256, 115456, 1710592, 26468352, 423641088, 6966960128, 117148778496, 2006711795712, 34918458982400, 615857321410560, 10989673088286720, 198124551844921344, 3604297438589878272, 66099459892606664704, 1220968511518137122816, 22700172671958160244736, 424526793381853406429184
Offset: 4
Original entry on oeis.org
1, 16, 208, 2848, 41216, 624384, 9812992, 158883840, 2636197888, 44640468992, 769058340864, 13445805899776, 238091742740480, 4263121901322240, 77082929745887232, 1405899615605096448, 25841135069123575808, 478285335973855232000, 8908149312942805876736, 166863051347010382725120
Offset: 5
Original entry on oeis.org
1, 30, 560, 9440, 156592, 2613664, 44169600, 756712960, 13136471040, 230851792896, 4102116843520, 73626174750720, 1333446495436800, 24347500823838720, 447847464256929792, 8292879605769961472, 154496591977544417280, 2894283145228079595520, 54496565896255729827840, 1030917988055843180904448
Offset: 6
Original entry on oeis.org
1, 48, 1240, 25864, 496944, 9234368, 169378560, 3095526912, 56624998400, 1039080697856, 19147850612736, 354499096477696, 6594549035106304, 123254413518962688, 2314187071702433792, 43639888872132837376, 826342030562687975424, 15708220978126028537856, 299700151992553060696064
Offset: 7
Original entry on oeis.org
1, 70, 2408, 61712, 1377600, 28663040, 574139904, 11259283200, 218198045184, 4201424145408, 80643838062592, 1546163834421248, 29648492642205696, 569064815285895168, 10938353882330562560, 210623966993992122368, 4063570313100983795712, 78558517204195934732288, 1521880839150792578433024
Offset: 8
Original entry on oeis.org
1, 96, 4256, 132480, 3430528, 80104448, 1758695424, 37158281984, 765948707328, 15534537453568, 311681600004096, 6208696187633664, 123091007914770432, 2432892993997766656, 47996192255918997504, 945900094339720151040, 18633845662960307929088, 367087117998177057243136, 7234078496745600613089280
Offset: 9
Original entry on oeis.org
1, 126, 7008, 261648, 7826544, 205083936, 4944057984, 112834665216, 2481031718144, 53154302311936, 1117907385569280, 23198258406862848, 476700713349279744, 9725111087129763840, 197341040692081557504, 3988586127032474271744, 80380982576880196780032, 1616460856969040046850048, 32457783381454315268866048
Offset: 10
A106651
c(n) = number of c-nets on n vertices.
Original entry on oeis.org
1, 1, 7, 73, 879, 11713, 167423, 2519937, 39458047, 637446145, 10561615871, 178683815937, 3076487458815, 53766284722177, 951817354412031, 17039752595865601, 308068940431556607, 5618467344224354305
Offset: 3
Daniel Johannsen (johannse(AT)informatik.hu-berlin.de), May 12 2005
c(0)=c(1)=1 because the only c-nets on 3 respectively 4 vertices are the complete graphs.
- Gheorghe Coserea, Table of n, a(n) for n = 3..302
- M. Bodirsky, C. Groepl, D. Johannsen and M. Kang, A Direct Decomposition of 3-connected Planar Graphs, conference paper (FPSAC05).
- Gheorghe Coserea, Algebraic equation for g.f.
- R. C. Mullin, P. J. Schellenberg, The enumeration of c-nets via quadrangulations, J. Combinatorial Theory 4 1968 259--276. MR0218275 (36 #1362).
-
c[0] = 1; c[1] = 1; c[2] = 7; c[3] = 73; c[4] = 879; c[5] = 11713; c[6] = 167423; c[7] = 2519937; c[n_] := c[n] = ( (-189665280 + 134270976 n - 31309824 n^2 + 2408448 n^3) c[n - 7] + (-479162880 + 376680448 n - 98932224 n^2 + 8692736 n^3) c[n - 6] + (-446660160 + 384601888 n - 112131264 n^2 + 11026784 n^3) c[n - 5] + (-183645792 + 168826836 n - 52598160 n^2 + 5361276 n^3) c[n - 4] + (-25324080 + 24563948 n - 6853668 n^2 + 418816 n^3) c[n - 3] + (1156086 - 2064937 n + 1206966 n^2 - 180467 n^3) c[n - 2] + (-3192 + 4842 n - 29796 n^2 + 18930 n^3) c[n - 1] ) / (126 + 693 n + 1134 n^2 + 567 n^3);
-
x='x; y='y;
system("wget http://oeis.org/A106651/a106651.txt");
Fxy = read("a106651.txt");
seq(N) = {
my(y0 = 1 + O('x^N), y1=0);
for (k = 1, N,
y1 = y0 - subst(Fxy, y, y0)/subst(deriv(Fxy, y), y, y0);
if (y1 == y0, break()); y0 = y1);
Vec(y0);
};
seq(18) \\ Gheorghe Coserea, Jan 08 2017
-
A290326(n,k) = {
if (n < 3 || k < 3, return(0));
sum(i=0, k-1, sum(j=0, n-1,
(-1)^((i+j+1)%2) * binomial(i+j, i)*(i+j+1)*(i+j+2)/2*
(binomial(2*n, k-i-1) * binomial(2*k, n-j-1) -
4 * binomial(2*n-1, k-i-2) * binomial(2*k-1, n-j-2))));
};
a(n) = if (n==3, 1, sum(k = (n+3)\2, 2*n-5, A290326(n-1, k)));
vector(18, n, a(n+2)) \\ Gheorghe Coserea, Jul 28 2017
Showing 1-8 of 8 results.
Comments