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A068563
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Numbers n such that 2^n (mod n) = 4^n (mod n).
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5
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1, 2, 4, 6, 8, 12, 16, 18, 20, 24, 32, 36, 40, 42, 48, 54, 60, 64, 72, 80, 84, 96, 100, 108, 120, 126, 128, 136, 144, 156, 160, 162, 168, 180, 192, 200, 216, 220, 240, 252, 256, 272, 288, 294, 300, 312, 320, 324, 336, 342, 360, 378, 384, 400, 408, 420, 432, 440
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| If k is in the sequence then 2k is also in the sequence, but the converse is not true.
Almost the same as A124240, numbers n such that lambda(n) divides n, where lambda(n) is Carmichael's lambda function, A002322. - T. D. Noe (noe(AT)sspectra.com), May 30 2003
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LINKS
| T. D. Noe, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Carmichael Function
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MATHEMATICA
| Select[Range[500], PowerMod[2, #, # ] == PowerMod[4, #, # ] & ]
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CROSSREFS
| Cf. A002322.
Sequence in context: A174973 A191743 A177807 * A124240 A068997 A067712
Adjacent sequences: A068560 A068561 A068562 * A068564 A068565 A068566
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KEYWORD
| easy,nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 25 2002
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EXTENSIONS
| Comment and Mathematica program corrected by T. D. Noe (noe(AT)sspectra.com), Oct 17 2008
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