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A007144 E-trees with exactly 3 colors.
(Formerly M5014)
0
0, 0, 0, 16, 177, 1374, 9370, 60582, 383577, 2412331, 15179013, 95860821, 608523299, 3884620950, 24937791531, 160952346541, 1044035753142, 6803694176919, 44526622599370, 292538816181867, 1928821043343096, 12758939344710713 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

REFERENCES

G. Gati, F. Harary and R. W. Robinson, Line colored trees with extendable automorphisms, Acta Math. Scientia, 2 (1982), 105-110.

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..22.

G. Gati, F. Harary, R. W. Robinson, Line colored trees with extendable automorphisms, Acta Mathematica Scientia 2.1 (1982), 105-110. (Annotated scanned copy)

Index entries for sequences related to trees

FORMULA

a(n) = A007142(n) - 3 * A007141(n) + 3 * A003238(n) for n > 1. - Sean A. Irvine, Oct 30 2017

CROSSREFS

Sequence in context: A070030 A283278 A231127 * A017521 A226507 A264297

Adjacent sequences:  A007141 A007142 A007143 * A007145 A007146 A007147

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(6) corrected and more terms from Sean A. Irvine, Oct 30 2017

STATUS

approved

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Last modified January 22 09:52 EST 2019. Contains 319363 sequences. (Running on oeis4.)