

A223699


Least number whose Collatz (3x+1) iteration has its maximum value at position n (counting from 1).


2



1, 2, 4, 8, 3, 32, 21, 20, 13, 80, 15, 7, 96, 69, 68, 45, 93, 19, 61, 56, 37, 51, 72, 49, 39, 33, 43, 133, 79, 260, 115, 349, 255, 127, 27, 157, 135, 279, 123, 421, 375, 727, 219, 723, 447, 295, 740, 493, 439, 591, 657, 1281, 1159, 877, 759, 615, 519, 1603
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OFFSET

1,2


COMMENTS

The maximum values are in A223700.


LINKS

T. D. Noe, Table of n, a(n) for n = 1..800


EXAMPLE

The Collatz iteration of 15 is {15, 46, 23, 70, 35, 106, 53, 160, 80, 40, 20, 10, 5, 16, 8, 4, 2, 1}. The maximum is 160, which occurs at position 11, counting from the right. Hence, a(11) = 15 because no number smaller than 15 has its maximum value at the 11 position.


MATHEMATICA

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; t= Table[c = Reverse[Collatz[n]]; Position[c, Max[c]][[1, 1]], {n, 10000}]; t2 = {}; n = 0; While[n++; p = Position[t, n, 1, 1]; p != {}, AppendTo[t2, p[[1, 1]]]]; t2


CROSSREFS

Cf. A070165 (Collatz iteration of n), A223700.
Sequence in context: A243505 A243065 A289271 * A231610 A225124 A059884
Adjacent sequences: A223696 A223697 A223698 * A223700 A223701 A223702


KEYWORD

nonn


AUTHOR

T. D. Noe, Mar 26 2013


STATUS

approved



