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 A338409 a(n) is the number of nodes with depth of n in a binary tree defined as: root = 1 and a child (C) of a node (N) is such that A338215(C) = N. For nodes with two children, the smaller child is assigned as the left child and the bigger one as the right child. A child of a one-child node is assigned as the left child. 0
 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 2, 3, 2, 3, 4, 3, 4, 3, 4, 4, 4, 4, 6, 6, 5, 6, 4, 4, 6, 7, 7, 6, 7, 6, 5, 4, 6, 7, 8, 8, 8, 8, 10, 8, 8, 8, 9, 10, 8, 9, 11, 13, 11, 9, 12, 11, 10, 11, 11, 11, 13, 11, 14, 14, 13, 15, 17, 15, 16, 16, 16, 14, 14, 14 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS EXAMPLE The binary tree, read from left to right in the order of increasing depth n, is the positive integer sequence A000027. The first 67 numbers are shown in the figure below.     1   (2)\_3      (4)\_5          6 \_(7)         8        9     (10)\_11          12 \___________13         14            (15)        16 \______17      (18)\_19   20           21   22 \_(23)          24   25        (26)  27             28 \______29            30 \_(31) 32           33        34          35        36 \_____________________37        (38)       39                       40 \_(41)                  42 \______43             44                 45        46 \______47  (48)                49        50        51               52 \_(53) 54        55             (56)       57        58 \_(59)                       60 \_(61) 62   63                      64        65   66 \_67 All left children except 2 are composite numbers and all prime numbers are right children. PROG (Python) from sympy import primepi def depth(k):     d = 0     while k > 1:         k -= primepi(k)         k += primepi(k)         d += 1     return d m = 1 for n in range (0, 101):     a = 0     while depth(m + a) == n:         a += 1     print(a)     m += a CROSSREFS Cf. A000027, A062298, A095117, A338215, A338237, A338260. Sequence in context: A214774 A320107 A190321 * A238890 A266968 A237593 Adjacent sequences:  A338406 A338407 A338408 * A338410 A338411 A338412 KEYWORD nonn AUTHOR Ya-Ping Lu, Oct 24 2020 STATUS approved

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Last modified April 15 01:24 EDT 2021. Contains 342974 sequences. (Running on oeis4.)