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 A309994 Number of forests of rooted trees with 2n colored nodes using exactly n colors. 2
 1, 2, 89, 14845, 5613775, 3809941836, 4073969863427, 6316651717425358, 13407079935176225215, 37344967651943608528498, 132181958309965092862822183, 579566807739313784043087337938, 3083812115454145185391757131500066, 19577110356940490275990571617295644659 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..187 FORMULA a(n) = A256064(2*n+1,n). MAPLE b:= proc(n, k) option remember; `if`(n<2, n, (add(add(d*b(d, k),       d=numtheory[divisors](j))*b(n-j, k)*k, j=1..n-1))/(n-1))     end: a:= n-> add(b(2*n+1, n-i)*(-1)^i*binomial(n, i), i=0..n): seq(a(n), n=0..15); CROSSREFS Cf. A256064. Sequence in context: A246871 A024239 A338734 * A339581 A256962 A266807 Adjacent sequences:  A309991 A309992 A309993 * A309995 A309996 A309997 KEYWORD nonn AUTHOR Alois P. Heinz, Aug 26 2019 STATUS approved

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Last modified May 14 07:13 EDT 2021. Contains 343879 sequences. (Running on oeis4.)