OFFSET
1,2
COMMENTS
The graph of the sequence looks like a staircase: the consecutive terms differ very little, then rise significantly, then again differ very little and so on. Could someone explain this behavior?
EXAMPLE
As n = 26 is the least number with the trajectory of length 5, (26, 27, 35, 39, 41), a(5) = 26.
MATHEMATICA
Clear[f, it, order, seq]; f[n_]:=f[n]=n-1+n/FactorInteger[n][[-1]][[1]]; it[k_, n_]:=it[k, n]=f[it[k, n-1]]; it[k_, 1]=k; order[n_]:=order[n]=SelectFirst[Range[1, 100], it[n, #]==it[n, #+1]&]; seq[n_]:=seq[n]=SelectFirst[Range[350000], order[#]==n&]; seq/@Range[61]
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Elijah Beregovsky, Feb 16 2020
STATUS
approved