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A007164 Number of P-graphs with 2n edges.
(Formerly M1784)

%I M1784

%S 1,2,7,31,167,999,6495,44619,319463,2356406,17775821,136405506,

%T 1060866006,8339982193,66147792753,528559162227,4250413757583,

%U 34368723106860,279254390054538,2278795583070154,18667432144042678,153452484745198722

%N Number of P-graphs with 2n edges.

%D R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math., 31 (1986), 47-63.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%F a(n) = (A003169(n) + 2 * A007165(n) + A007163(n)) / 4. - _Sean A. Irvine_, Nov 06 2017

%Y Cf. A003169, A007163, A007165.

%K nonn

%O 1,2

%A _N. J. A. Sloane_

%E a(5), a(9), a(10) corrected and more terms from _Sean A. Irvine_, Nov 06 2017

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Last modified January 20 23:20 EST 2020. Contains 331104 sequences. (Running on oeis4.)