Record Collatz (3x+1) pairs (see comments).
3, 5, 7, 12, 9, 13, 27, 102, 703, 131, 937, 133, 1249, 134, 2223, 141, 2463, 159, 2919, 165, 10087, 170, 13449, 171, 35655, 222, 60975, 254, 142587, 273, 381727, 282, 626331, 310, 837799, 342, 1126015, 364, 1394431, 380, 6206655, 406, 6649279, 492, 10507503, 496
1
This sequence gives the pairs of numbers c and len such that the Collatz iteration starting with c produces a record number (len) of Collatz terms greater than c. For example, the number 3 products the Collatz iteration 3, 10, 5, 16, 8, 4, 2, 1 which has 5 terms greater than 3.
T. D. Noe, Plot of 30 pairs
T. D. Noe, Table of 30 pairs
Wikipedia, Collatz conjecture
(Mma) Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; mx = 1; t = {}; Do[cnt = Length[Select[Collatz[n], # > n &]]; If[cnt > mx, mx = cnt; AppendTo[t, {n, cnt}]], {n, 3, 2^15, 2}]; t
nonn,tabl
T. D. Noe, May 05 2017