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A258592
Values of k such that the number of rooted trees with k nodes (A000081(k)) is even.
3
0, 3, 4, 6, 7, 9, 11, 12, 13, 19, 20, 21, 24, 26, 29, 31, 32, 34, 36, 37, 39, 41, 43, 44, 45, 46, 47, 48, 51, 52, 53, 54, 55, 57, 58, 59, 60, 62, 63, 66, 69, 70, 72, 79, 80, 81, 83, 85, 86, 88, 89, 90, 91, 92, 94, 95, 96, 97, 100, 101, 102, 103, 105, 106, 107
OFFSET
1,2
COMMENTS
Complement of A263831.
LINKS
MATHEMATICA
Module[{t}, t[1] = 1; t[k_] := t[k] = Sum[DivisorSum[k-m, t[#] # &] t[m]/(k-1), {m, k-1}]; Select[Range[0, 107], EvenQ@t[#] &]] (* after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved