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A054788
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Earliest sequence with a(a(n))=8n.
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0
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0, 2, 8, 4, 24, 6, 40, 9, 16, 56, 11, 80, 13, 96, 15, 112, 64, 18, 136, 20, 152, 22, 168, 25, 32, 184, 27, 208, 29, 224, 31, 240, 192, 34, 264, 36, 280, 38, 296, 41, 48, 312, 43, 336, 45, 352, 47, 368, 320, 50, 392, 52, 408, 54, 424, 57, 72, 440, 59, 464, 61, 480, 63, 496
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Index entries for sequences of the a(a(n)) = 2n family
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MATHEMATICA
| nmax = 63; amax = 8*nmax; t = {{0, a[0] = 0}, {1, a[1] = 2}, {2, a[2]}}; While[ !FreeQ[t, a], t = Table[{n, a[n]}, {n, 0, nmax}]; n = Select[t, !IntegerQ[ #[[2]] ] &, 1][[1, 1]]; t2 = Union[ Flatten[ Append[ Select[ t, IntegerQ[ #[[2]] ] &], n]]]; an = If[n == 2, 8, Select[ Complement[ Range[ Max[t2] ], t2], Mod[#, 8] != 0 &, 1][[1]] ]; a[n] = an; While[ an < amax, an = a[n = an] = 8 n]]; Table[ a[n], {n, 0, nmax}] (* From Jean-François Alcover, Jan 11 2012 *)
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CROSSREFS
| Cf. A002516, A002517, A002518, A007379.
Sequence in context: A104772 A088156 A019193 * A193851 A193847 A019194
Adjacent sequences: A054785 A054786 A054787 * A054789 A054790 A054791
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KEYWORD
| nice,nonn
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Apr 27 2000
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