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 A000087 Number of unrooted nonseparable planar maps with n edges and a distinguished face. (Formerly M1240 N0474) 11
 2, 1, 2, 4, 10, 37, 138, 628, 2972, 14903, 76994, 409594, 2222628, 12281570, 68864086, 391120036, 2246122574, 13025721601, 76194378042, 449155863868, 2666126033850, 15925105028685, 95664343622234, 577651490729530 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The number of unrooted non-separable n-edge maps in the plane (planar with a distinguished outside face). - Valery A. Liskovets, Mar 17 2005 REFERENCES V. A. Liskovets and T. R. Walsh, Enumeration of unrooted maps on the plane, Rapport technique, UQAM, No. 2005-01, Montreal, Canada, 2005. 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). LINKS T. D. Noe, Table of n, a(n) for n=1..200 W. G. Brown, Enumeration of non-separable planar maps, Canad. J. Math., 15 (1963), 526-545. W. G. Brown, Enumeration of non-separable planar maps V. A. Liskovets and T. R. Walsh, Counting unrooted maps on the plane, Advances in Applied Math., 36, No.4 (2006), 364-387. FORMULA a(n) = (1/3n)[(n+2)binomial(3n, n)/((3n-2)(3n-1)) + Sum_{0

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Last modified December 5 06:35 EST 2022. Contains 358582 sequences. (Running on oeis4.)