A224303 Numbers n for which number of iterations to reach the largest equals number of iterations to reach 1 from the largest in Collatz (3x+1) trajectory of n.
1, 6, 120, 334, 335, 804, 1249, 2008, 2010, 2012, 2013, 6556, 6557, 6558, 6801, 6802, 6803, 7496, 7498, 7500, 7501, 7505, 10219, 22633, 25182, 25183, 27074, 27075, 27864, 27866, 27868, 31838, 31839, 32078, 36630, 36633, 36690, 36691, 36914, 39126, 39344
Offset: 1
Keywords
Examples
6 is in the list because Collatz trajectory of 6 is {6, 3, 10, 5, 16, 8, 4, 2, 1} and number of steps to reach largest = number of steps to reach 1 from largest = 4.
Links
- T. D. Noe, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3*# + 1] &, n, # > 1 &]; Select[Range[50000],Position[Collatz[#],Max[Collatz[#]]] == {{(Length[Collatz[#]] + 1)/2}} &]
Comments