

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
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OFFSET

0,3


REFERENCES

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


LINKS



FORMULA

a(n) = coefficient of x^(2n+1) in x + D(x)^3/(1D(x)^2) where D(x) = Sum_{k=0..infinity} A007162(k) * x^(2*k+1).  Sean A. Irvine, Nov 06 2017


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



