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A126099 Number of 3-indecomposable (connected) graphs on n nodes. 3
1, 1, 1, 2, 6, 21, 7, 10, 10, 15, 15, 21, 21, 28, 28, 36, 36, 45, 45, 55, 55, 66, 66, 78, 78, 91, 91, 105, 105, 120, 120, 136, 136, 153, 153, 171, 171, 190, 190, 210, 210, 231, 231, 253, 253, 276, 276, 300, 300, 325, 325, 351, 351, 378, 378, 406, 406, 435, 435, 465, 465, 496 (list; graph; refs; listen; history; internal format)
OFFSET

1,4

COMMENTS

See A124593 for definition.

FORMULA

G.f.: x/((1-x)*(1-x^2)^2) + 1 - x^3 + 3*x^4 + 15*x^5 + x^6.

CROSSREFS

Cf. A128526, A128527, A128528

Sequence in context: A074859 A162682 A103160 * A063753 A066893 A004192

Adjacent sequences:  A126096 A126097 A126098 * A126100 A126101 A126102

KEYWORD

nonn

AUTHOR

David Applegate (david(AT)research.att.com) and N. J. A. Sloane (njas(AT)research.att.com), Mar 05 2007

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Last modified February 16 21:51 EST 2012. Contains 205978 sequences.