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 A260403 Number of unlabeled rooted trees with n nodes where the outdegrees (branching factors) of adjacent nodes differ by at most one. 4
 0, 1, 1, 1, 1, 2, 3, 5, 8, 14, 24, 43, 76, 138, 250, 460, 848, 1576, 2939, 5516, 10382, 19629, 37221, 70820, 135097, 258426, 495460, 952083, 1833176, 3536502, 6834408, 13229829, 25649202, 49799891, 96821854, 188485968, 367375883, 716872030, 1400373358 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,6 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..400 EXAMPLE a(5) = 2: :    o      o :    |     / \ :    o    o   o :    |    |   | :    o    o   o :    | :    o :    | :    o MAPLE b:= proc(n, i, h, v) option remember; `if`(n=0, `if`(v=0, 1, 0),       `if`(i<1 or v<1 or n add(b(n-1\$2, j\$2), j=0..n-1): seq(a(n), n=0..40); MATHEMATICA b[n_, i_, h_, v_] := b[n, i, h, v] = If[n==0, If[v==0, 1, 0], If[i<1 || v<1 || n

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Last modified February 27 15:59 EST 2020. Contains 332307 sequences. (Running on oeis4.)