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A339785 Number of homeomorphically irreducible leaf colored trees with n leaves using exactly 2 colors. 4
0, 1, 2, 7, 24, 91, 354, 1491, 6504, 29711, 139616, 674696, 3328798, 16730955, 85382210, 441571216, 2310003732, 12206975528, 65082858008, 349756996762, 1892980028014, 10310987833049, 56489307860860, 311112321625754, 1721692801914844, 9569930999155801, 53410232801675436 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
a(n) = A339782(n) - 2*A007827(n).
PROG
(PARI) my(N=25); (U(N, 2)-2*U(N, 1))[2..1+N] \\ See A339780 for U(n, k).
CROSSREFS
Column k=2 of A339780.
Sequence in context: A150394 A151294 A196470 * A150395 A150396 A150397
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Dec 16 2020
STATUS
approved

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Last modified March 29 01:36 EDT 2024. Contains 371264 sequences. (Running on oeis4.)