A225124 a(n) = least number k such that 2^n is highest in Collatz(3x+1) trajectory of k.

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

Offset: 0

Author

Jayanta Basu, Apr 29 2013

Keywords

• nonn

Examples

			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.
		

Crossrefs

Cf. A000079, A025586, A095381, A231610.

Programs

Haskell

a225124 = (+ 1) . fromJust . (`elemIndex` a025586_list) . a000079
-- Reinhard Zumkeller, Apr 30 2013

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