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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: A356942 A151484 A275871 * A352815 A007167 A036728
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 May 21 08:24 EDT 2024. Contains 372729 sequences. (Running on oeis4.)