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A289991 Number of connected graphs of degree at most 4 with at least a cyclic structure and a node of degree one. 2
1, 0, 0, 0, 1, 7, 35, 181, 1027, 6551, 47356, 383353, 3439508, 33796286, 360254030 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

COMMENTS

Number of alkyl-n-cycloalkanes with n carbon atoms (the pure n-cycloalkanes aren't counted here).

Stereoisomerism is not taken into account. Some of the drawn structures may or may not exist due to their strained geometries.

LINKS

Table of n, a(n) for n=0..14.

FORMULA

a(n) = A289159(n) - A289990(n).

EXAMPLE

a(5) = 7 because there are 7 structures with 5 carbons following the rule above: 1,1-dimethylcyclopropane, 1,2-dimethylcyclopropane, ethylcyclopropane, methylcyclobutane, 1-methylbicyclobutane, 2-methylbicyclobutane, methyltetrahedrane.

CROSSREFS

Cf. A121941, A289159, A289989, A289990.

Sequence in context: A037689 A051926 A297602 * A295248 A295647 A026128

Adjacent sequences:  A289988 A289989 A289990 * A289992 A289993 A289994

KEYWORD

nonn,more

AUTHOR

Natan Arie' Consigli, Aug 03 2017

STATUS

approved

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Last modified July 19 22:14 EDT 2019. Contains 325168 sequences. (Running on oeis4.)