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A322928 a(0)=1; for n>0, a(n) is the number of rooted 3-regular maps with 2n vertices on the projective plane. 0
1, 9, 118, 1773, 28650, 484578, 8457708, 151054173, 2745685954, 50606020854, 943283037684 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..10.

Evgeniy Krasko, Alexander Omelchenko, Enumeration of r-regular maps on the torus. Part I: Rooted maps on the torus, the projective plane and the Klein bottle. Sensed maps on the torus, Discrete Mathematics (2019) Vol. 342, Issue 2, 584-599. Also arXiv:1709.03225 [math.CO]. See Th. 3.3 and Table 2.

FORMULA

Theorem 3.3 gives an explicit formula.

CROSSREFS

Sequence in context: A081629 A051617 A166823 * A087984 A197544 A234964

Adjacent sequences:  A322925 A322926 A322927 * A322929 A322930 A322931

KEYWORD

nonn,more

AUTHOR

Evgeniy Krasko, Dec 31 2018

EXTENSIONS

Added initial term a(0)=1 to match Taylor series expansion in Theorem 3.3. Deleted incorrect formula and associated Python program. - N. J. A. Sloane, Jan 11 2019

STATUS

approved

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Last modified October 14 05:08 EDT 2019. Contains 327995 sequences. (Running on oeis4.)