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 A007161 Number of blobs with vertical symmetry. (Formerly M3503) 1
 1, 1, 4, 15, 62, 262, 1148, 5123, 23316, 107570, 502664, 2372786, 11302858, 54256236, 262226900, 1274944859, 6231845040, 30605344282, 150948390672, 747356368322, 3713140528364, 18506907541124, 92509837573736, 463660345091686 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math. 31 (1986) no 1, 47-63. FORMULA a(n) = coefficient of x^(2n+1) in x + D(x)^3/(1-D(x)^2) where D(x) = Sum_{k=0..infinity} A007162(k) * x^(2*k+1). - Sean A. Irvine, Nov 06 2017 CROSSREFS Cf. A007162. Sequence in context: A285363 A151484 A275871 * A007167 A036728 A027216 Adjacent sequences:  A007158 A007159 A007160 * A007162 A007163 A007164 KEYWORD nonn AUTHOR EXTENSIONS a(9) corrected and more terms from Sean A. Irvine, Nov 06 2017 STATUS approved

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Last modified December 6 14:47 EST 2019. Contains 329806 sequences. (Running on oeis4.)