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A005959 Number of acyclic ethylene derivatives with n carbon atoms.
(Formerly M3286)
0
1, 1, 4, 6, 18, 42, 118, 314, 895, 2521, 7307, 21238, 62566, 185310, 553288, 1660490, 5011299, 15190665, 46244031, 141296042, 433204573, 1332261200, 4108833222, 12704949506, 39379343929, 122327632914, 380778749899, 1187544117426 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

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=2..29.

R. C. Read, The Enumeration of Acyclic Chemical Compounds, pp. 25-61 of A. T. Balaban, ed., Chemical Applications of Graph Theory, Ac. Press, 1976. [Annotated scanned copy] See p. 44.

FORMULA

G.f.: (1/4)*x^2*(B(x)^4+3*B(x^2)^2) where B(x) is the g.f. for A000625. - Sean A. Irvine, Nov 12 2016

EXAMPLE

G.f. = x^2 + x^3 + 4*x^4 + 6*x^5 + 18*x^6 + 42*x^7 + 118*x^8 + 314*X^9 + ...

CROSSREFS

Sequence in context: A235344 A060667 A218065 * A057393 A196570 A274992

Adjacent sequences:  A005956 A005957 A005958 * A005960 A005961 A005962

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Sean A. Irvine, Nov 12 2016

STATUS

approved

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Last modified January 16 03:15 EST 2019. Contains 319184 sequences. (Running on oeis4.)