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A087272
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a(n) is the largest prime number in 3x+1 trajectory initiated at n;.
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3
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2, 5, 2, 5, 5, 17, 2, 17, 5, 17, 5, 13, 17, 53, 2, 17, 17, 29, 5, 2, 17, 53, 5, 29, 13, 1619, 17, 29, 53, 1619, 2, 29, 17, 53, 17, 37, 29, 101, 5, 1619, 2, 43, 17, 17, 53, 1619, 5, 37, 29, 29, 13, 53, 1619, 1619, 17, 43, 29, 101, 53, 61, 1619, 1619, 2, 37, 29, 101, 17, 13, 53
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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MATHEMATICA
| c[x_] := (1-Mod[x, 2])*(x/2)+Mod[x, 2]*(3*x+1); c[1]=1; fpl[x_] := Delete[FixedPointList[c, x], -1] ofp[x_] := Part[fpl[x], Flatten[Position[PrimeQ[fpl[x]], True]]] Table[Max[ofp[w]], {w, 1, 256}]
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CROSSREFS
| Cf. A025586, A087232.
Sequence in context: A082881 A104289 A177435 * A107060 A016589 A151572
Adjacent sequences: A087269 A087270 A087271 * A087273 A087274 A087275
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Sep 18 2003
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