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A225124 a(n) = least number k such that 2^n is highest in Collatz(3x+1) trajectory of k. 3
1, 2, 4, 8, 3, 32, 21, 128, 85, 512, 151, 2048, 1365, 8192, 5461, 32768, 14563, 131072, 87381, 524288, 349525, 2097152, 932067, 8388608, 5592405, 33554432, 22369621, 134217728, 26512143, 536870912, 357913941 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..30.

EXAMPLE

a(4)=3 since 3 is the least number such that largest member of Collatz(3 x + 1) trajectory of 3 is 2^4 = 16.

MATHEMATICA

Coll[n_]:=NestWhileList[If[EvenQ[#], #/2, 3*#+1]&, n, #>1 &]; t={}; Do[i=1; While[Max[Coll[i]] != 2^n, i++]; AppendTo[t, i], {n, 0, 25}]; t

PROG

(Haskell)

a225124 = (+ 1) . fromJust . (`elemIndex` a025586_list) . a000079

-- Reinhard Zumkeller, Apr 30 2013

CROSSREFS

Cf. A000079, A025586, A095381, A231610.

Sequence in context: A289271 A223699 A231610 * A059884 A191561 A021805

Adjacent sequences:  A225121 A225122 A225123 * A225125 A225126 A225127

KEYWORD

nonn

AUTHOR

Jayanta Basu, Apr 29 2013

STATUS

approved

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Last modified October 16 02:42 EDT 2018. Contains 316252 sequences. (Running on oeis4.)