A007144 E-trees with exactly 3 colors. (Formerly M5014)

0, 0, 0, 16, 177, 1374, 9370, 60582, 383577, 2412331, 15179013, 95860821, 608523299, 3884620950, 24937791531, 160952346541, 1044035753142, 6803694176919, 44526622599370, 292538816181867, 1928821043343096, 12758939344710713

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 A323856 A226507

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