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A103938 Number of rooted non-separable n-edge maps in the plane (planar with a distinguished outside face). 1
3, 2, 5, 18, 77, 364, 1836, 9690, 52877, 296010, 1690845, 9817080, 57769740, 343806368, 2065802056, 12515350122, 76367432013, 468922828150, 2895381678735, 17966214519330, 111977263221285, 700704492237540, 4400559613086000, 27727270719559320, 175230257041962252 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

V. A. Liskovets and T. R. Walsh, Enumeration of unrooted maps on the plane, Rapport technique, UQAM, No. 2005-01, Montreal, Canada, 2005.

LINKS

Table of n, a(n) for n=1..25.

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) = (n+2)*A000139(n)/2.

MATHEMATICA

a[n_] := (n+2)(3(n-1))!/((2n-1)! n!);

Array[a, 30] (* Jean-François Alcover, Aug 29 2019 *)

CROSSREFS

Cf. A000139.

Sequence in context: A214502 A077039 A269155 * A304534 A085973 A302854

Adjacent sequences:  A103935 A103936 A103937 * A103939 A103940 A103941

KEYWORD

easy,nonn

AUTHOR

Valery A. Liskovets, Mar 17 2005

EXTENSIONS

More terms from Jean-François Alcover, Aug 29 2019

STATUS

approved

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Last modified May 30 19:03 EDT 2020. Contains 334728 sequences. (Running on oeis4.)