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A223700
The maximum value of the Collatz (3x+1) iteration beginning at A223699(n).
2
1, 2, 4, 8, 16, 32, 64, 20, 40, 80, 160, 52, 96, 208, 68, 136, 280, 88, 184, 56, 112, 232, 72, 148, 304, 100, 196, 400, 808, 260, 520, 1048, 13120, 4372, 9232, 472, 916, 1888, 628, 1264, 2536, 4912, 1672, 3256, 39364, 2248, 740, 1480, 2968, 5992, 1972, 3844
OFFSET
1,2
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) = 160 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}]; t3 = {}; n = 0; While[n++; p = Position[t, n, 1, 1]; p != {}, c = Collatz[p[[1, 1]]]; AppendTo[t3, Max[c]]]; t3
CROSSREFS
Cf. A070165 (Collatz iteration of n), A223699.
Sequence in context: A160686 A201920 A343926 * A036140 A036138 A000855
KEYWORD
nonn
AUTHOR
T. D. Noe, Mar 26 2013
STATUS
approved