

A005957


Number of acyclic ketone and aldehyde stereoisomers with n carbon atoms.
(Formerly M0880)


1



1, 1, 2, 3, 8, 18, 47, 123, 338, 935, 2657, 7616, 22138, 64886, 191873, 571169, 1711189, 5153883, 15599094, 47415931, 144692886, 443091572, 1361233280, 4194107380, 12957209782, 40128629400, 124562327944, 387467513732, 1207633413980
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OFFSET

1,3


COMMENTS

It seems that, starting with a(2), this is row j = 1 in Table 3 (p. 176) in Wang et al. (2003). This is also corroborated by the title of the table: "The numbers f_{ij} of stereo isomers of acyclic saturated compounds consisting of C, O, and H, C_i H_{2i+2} O_j". Such a claim, if true, can probably be proved by using Eqs. (5), (6), and (7) on pp. 175176 of the paper.  Petros Hadjicostas, Jul 24 2019


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=1..29.
R. C. Read, The Enumeration of Acyclic Chemical Compounds, pp. 2561 of A. T. Balaban, ed., Chemical Applications of Graph Theory, Ac. Press, 1976. [Annotated scanned copy] See p. 44.
Jianji Wang, Ruxiong Li, and Shen Wang, Enumeration of isomers of acyclic saturated hydroxyl ethers, Journal of Mathematical Chemistry 33 (2003), 171179.


FORMULA

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


CROSSREFS

Sequence in context: A241906 A079224 A002369 * A185171 A158448 A073192
Adjacent sequences: A005954 A005955 A005956 * A005958 A005959 A005960


KEYWORD

nonn


AUTHOR

N. J. A. Sloane.


EXTENSIONS

a(23) corrected, title improved, and more terms from Sean A. Irvine, Nov 12 2016


STATUS

approved



