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A339786 Number of homeomorphically irreducible leaf colored trees with n leaves using exactly 3 colors. 3
0, 0, 1, 9, 63, 412, 2673, 17571, 117365, 798819, 5530122, 38908380, 277750749, 2009160864, 14707923021, 108835512411, 813241695330, 6130521151377, 46584949832013, 356571373433217, 2747371943624943, 21296479544449677, 165994877608025730, 1300408539157086640 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..500

FORMULA

a(n) = A339783(n) - 3*A339782(n) + 3*A007827(n).

PROG

(PARI) my(N=25); (U(N, 3) - 3*U(N, 2) + 3*U(N, 1))[2..1+N] \\ See A339780 for U(n, k).

CROSSREFS

Column k=3 of A339780.

Cf. A007827, A339782, A339783, A339785.

Sequence in context: A111997 A016137 A230547 * A201885 A225964 A037508

Adjacent sequences: A339783 A339784 A339785 * A339787 A339788 A339789

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Dec 18 2020

STATUS

approved

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Last modified February 1 18:07 EST 2023. Contains 359995 sequences. (Running on oeis4.)