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A004066 Number of simple regular trivalent bicolored graphs with 2n nodes. 4
0, 0, 1, 1, 2, 6, 14, 41, 157, 725, 4196, 29817, 246646, 2297088, 23503564, 260265650, 3090341095, 39101587595, 524783295041, 7443251159470, 111222017297268, 1746166043555813, 28734210790531045, 494526547845483641, 8883866458982018870, 166286444108288113541, 3237719185652343485853, 65477290060076644381373 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..28.

Sean A. Irvine, On the difference between A004066 and A008325

FORMULA

a(n) = (A000840(n) + A000512(n))/2. - Andrew Howroyd, Apr 01 2020

CROSSREFS

Cf. A000512, A000840, A008325 (bipartite), A006823 (connected).

Sequence in context: A284998 A009423 A008325 * A123383 A225172 A212197

Adjacent sequences:  A004063 A004064 A004065 * A004067 A004068 A004069

KEYWORD

nonn

AUTHOR

Gunnar Brinkmann, Brendan McKay and Eric Rogoyski

EXTENSIONS

a(1)-a(2) prepended and terms a(15) and beyond from Andrew Howroyd, Apr 01 2020

STATUS

approved

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Last modified April 11 11:31 EDT 2021. Contains 342886 sequences. (Running on oeis4.)