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 A003693 Number of 2-factors in P_4 X P_n. 3
 0, 2, 3, 18, 54, 222, 779, 2953, 10771, 40043, 147462, 545603, 2013994, 7442927, 27490263, 101563680, 375176968, 1386004383, 5120092320, 18914660608, 69873991466, 258127586367, 953569519203, 3522660270539 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Ars Combin. 49 (1998), 129-154. LINKS Andrew Howroyd, Table of n, a(n) for n = 1..200 F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Preliminary version of paper that appeared in Ars Combin. 49 (1998), 129-154. F. Faase, Results from the counting program FORMULA a(n) = 2a(n-1) + 7a(n-2) - 2a(n-3) - 3a(n-4) + a(n-5), n > 5. G.f.: (-x*(x-1)*(x-2)*(x+1))/(-1 + x^5 - 3*x^4 - 2*x^3 + 7*x^2 + 2*x). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 10 2009 CROSSREFS Cf. A003776, A145400, A145415, A145417, A222202, A222203. Sequence in context: A137784 A053195 A211867 * A216628 A048047 A114165 Adjacent sequences:  A003690 A003691 A003692 * A003694 A003695 A003696 KEYWORD nonn AUTHOR STATUS approved

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Last modified November 18 21:04 EST 2018. Contains 317331 sequences. (Running on oeis4.)