OFFSET
0,2
EXAMPLE
a(4)=10 since A025587(4)=15 and starting with 15 in the Collatz sequence gives a maximum value of 160 with a blowup factor of 160/15 = 10.66666...
MATHEMATICA
With[{s = Array[Max@ NestWhileList[If[EvenQ@ #, #/2, 3 # + 1] &, #, # > 1 &]/# &, 2^18]}, Floor@ Union@ FoldList[Max, s]] (* Michael De Vlieger, Mar 13 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Larry Reeves (larryr(AT)acm.org), May 03 2001
STATUS
approved