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 A257654 Number of unlabeled rooted trees with n nodes where the outdegrees (branching factors) of adjacent nodes differ by exactly one. 4
 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 2, 2, 0, 1, 3, 3, 1, 2, 6, 6, 3, 6, 11, 11, 9, 15, 23, 24, 25, 39, 48, 52, 67, 96, 107, 122, 174, 242, 247, 295, 448, 598, 598, 744, 1141, 1493, 1493, 1913, 2898, 3730, 3826, 5003, 7362, 9396, 9980, 13201, 18757, 23840 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,14 COMMENTS These trees are also counted by A260353 and A260403. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..400 EXAMPLE a(5) = 1:     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..60); 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 January 19 04:14 EST 2019. Contains 319304 sequences. (Running on oeis4.)