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A068482
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Numbers n such that gcd(n!+1,2^n-1)>1.
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4
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2, 3, 4, 6, 10, 12, 16, 18, 22, 23, 28, 30, 36, 39, 40, 42, 46, 51, 52, 58, 60, 63, 66, 70, 72, 78, 82, 88, 95, 96, 99, 100, 102, 106, 108, 112, 126, 130, 131, 135, 136, 138, 148, 150, 156, 162, 166, 172, 178, 180, 183, 190, 191, 192, 196, 198, 210, 215, 222, 226
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OFFSET
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1,1
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COMMENTS
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If n=p-1, p prime, then n is in the sequence.
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LINKS
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G. C. Greubel, Table of n, a(n) for n = 1..1000
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MAPLE
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select(n->gcd(factorial(n)+1, 2^n-1)>1, [$1..230]); # Muniru A Asiru, Oct 16 2018
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MATHEMATICA
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Select[Range[300], GCD[#!+1, 2^#-1]>1&] (* Harvey P. Dale, Jan 31 2015 *)
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PROG
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(PARI) isok(n) = gcd(n!+1, 2^n-1) > 1; \\ Michel Marcus, Oct 16 2018
(GAP) Filtered([1..230], n->Gcd(Factorial(n)+1, 2^n-1)>1); # Muniru A Asiru, Oct 16 2018
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CROSSREFS
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Cf. A000225 (2^n-1), A038507 (n!+1).
Cf. A068480, A068481, A068483.
Sequence in context: A177913 A098392 A076850 * A068499 A137172 A069744
Adjacent sequences: A068479 A068480 A068481 * A068483 A068484 A068485
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre, Mar 10 2002
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STATUS
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approved
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