OFFSET
1,5
COMMENTS
Consider the binary tree illustrated in A005940: If we start from any n, computing successive iterations of A252463 until 1 is reached (i.e., we are traversing level by level towards the root of the tree, starting from that vertex of the tree where n is located at), a(n) gives the number of odd numbers > 1 encountered on the path (i.e., excluding the final 1 from the count but including the starting n if it was odd).
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
FORMULA
MATHEMATICA
a252735[n_] := Prepend[Rest@Array[PrimePi[FactorInteger[#][[-1]][[1]]] - 1 &, n], 0]; a252735[108] (* Michael De Vlieger, Dec 21 2014, after Stefan Steinerberger at A061395 *)
PROG
KEYWORD
nonn
AUTHOR
Antti Karttunen, Dec 21 2014
STATUS
approved