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A095388 Smallest initial value for 3x+1 trajectory, divisible by 2^n, such that emerging peak-value exceeds this start-value. 0
6, 12, 120, 432, 864, 1728, 3456, 6912, 931328, 4357120, 19789824, 249753600, 499507200, 1272561664, 5226070016, 10452140032, 351882051584, 1215818366976, 3364158439424, 6953815244800, 13907630489600, 27815260979200, 55630521958400, 1343005923475456 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Initial values divisible by 2^n involve in 3x+1 iteration n decreasing step, nevertheless can result peak value exceeding start-value.
LINKS
EXAMPLE
n=120=8.15,max=160>iv=120;
trajectory={120,60,30,15,46,23,70,35,106,53,160,80,40,20,10,5,16,8,4,2,1}
MATHEMATICA
c[x_]:=c[x]=(1-Mod[x, 2])*(x/2)+Mod[x, 2]*(3*x+1); c[1]=1; fpl[x_]:=Delete[FixedPointList[c, x], -1] {k=65536, ta=Table[0, {100}], u=1}; {$RecursionLimit=1000; m=0}; Do[If[Greater[Max[fpl[k*n]], k*n], Print[{k*n, n}]; ta[[u]]=k*n; u=u+1], {n, 1, 1000000}] [Code for 2^16 divisor, a(16)].
CROSSREFS
Cf. A025586.
Sequence in context: A144760 A207838 A191662 * A038515 A335735 A051586
KEYWORD
nonn
AUTHOR
Labos Elemer, Jun 14 2004
EXTENSIONS
a(17)-a(24) from Donovan Johnson, Feb 02 2011
STATUS
approved

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Last modified March 28 14:33 EDT 2024. Contains 371254 sequences. (Running on oeis4.)