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A129293
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Numbers m such that m^4-1 has no divisors d with 1<d<m-1.
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4
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3, 4, 6, 150, 180, 240, 270, 420, 570, 1290, 1320, 2310, 2550, 2730, 3360, 3390, 4260, 4650, 5850, 5880, 6360, 6780, 9000, 9240, 9630, 10530, 10890, 11970, 13680, 13830, 14010, 14550, 16230, 16650, 18060, 18120, 18540, 19140, 19380, 21600, 21840, 23370
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OFFSET
| 1,1
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COMMENTS
| A129292(a(n)) = #{1, a(n)-1} = 2.
Essentially the same as A070155, since m^4-1=(m-1)(m+1)(1+m^2). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 14 2008
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EXAMPLE
| {1,5,7,35,37,185,259,1295} is the set of divisors of 6^4-1, therefore 6 is a term, A129292(6) = #{1,3} = 2.
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CROSSREFS
| Cf. A129295, A129297.
Sequence in context: A019209 A019120 A066466 * A049010 A095877 A024476
Adjacent sequences: A129290 A129291 A129292 * A129294 A129295 A129296
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 09 2007
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