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 A354227 Odd numbers whose Collatz trajectory contains exactly 12 odd numbers. 0
 39, 79, 153, 157, 305, 307, 315, 317, 611, 613, 629, 631, 647, 683, 687, 1221, 1229, 1241, 1257, 1261, 1265, 1269, 1295, 1353, 1367, 1369, 1375, 1505, 2445, 2453, 2481, 2483, 2489, 2507, 2515, 2517, 2521, 2525, 2531, 2545, 2589, 2593, 2633, 2705, 2707, 2733 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..46. FORMULA { A005408 } intersect { A072122 }. EXAMPLE 305 is a term since its Collatz trajectory is 305, 916, 458, 229, 688, 344, 172, 86, 43, 130, 65, 196, 98, 49, 148, 74, 37, 112, 56, 28, 14, 7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1. MATHEMATICA q[n_] := Count[NestWhileList[If[OddQ[#], 3 # + 1, #/2] &, n, # > 1 &], _?OddQ] == 12; Select[Range[1, 2750, 2], q] (* Amiram Eldar, May 20 2022 *) CROSSREFS Cf. A005408, A072122. Sequence in context: A355852 A290815 A355857 * A063335 A020264 A044177 Adjacent sequences: A354224 A354225 A354226 * A354228 A354229 A354230 KEYWORD nonn AUTHOR Krishna Kumar Arumugam, May 20 2022 STATUS approved

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Last modified August 13 20:02 EDT 2024. Contains 375144 sequences. (Running on oeis4.)