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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

Table of n, a(n) for n=0..23.

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

N. J. A. Sloane.

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.)