OFFSET
3,1
COMMENTS
Question. Is the sequence bounded?
By private communication from Alois P. Heinz, the places of records are 3, 4, 6, 286, 29866 with values 2, 3, 6, 8, 10. No more up to 46000000.
LINKS
EXAMPLE
For n=52 we have iterations: P^(1)=157, P^(2)=59, P^(3)=89, P^(4)=67, P^(5)=101, P^(6)=19<52. Thus a(52)=6.
MATHEMATICA
P[n_] := FactorInteger[3*n + 1][[-1, 1]]; Table[k = 1; m = n; While[m = P[m]; m >= n, k++]; k, {n, 3, 100}] (* T. D. Noe, Oct 30 2011 *)
PROG
(PARI) a(n) = {nb = 1; na = n; while((nna=vecmax(factor(3*na+1)[, 1])) >= n, na = nna; nb++); nb; } \\ Michel Marcus, Feb 06 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Oct 29 2011
STATUS
approved