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A068480
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Numbers n such that gcd(n!-1,2^n+1)>1.
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5
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1, 29, 41, 53, 69, 105, 125, 141, 153, 165, 189, 233, 249, 273, 293, 321, 329, 405, 413, 429, 441, 453, 485, 581, 585, 629, 641, 653, 713, 729, 741, 761, 765, 809, 813, 849, 893, 905, 989, 993, 1005, 1013, 1041, 1049, 1089, 1121, 1125, 1133, 1169, 1205
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OFFSET
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1,2
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LINKS
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MAPLE
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select(n->gcd(factorial(n)-1, 2^n+1)>1, [$1..1230]); # Muniru A Asiru, Oct 16 2018
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MATHEMATICA
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Select[Range[2500], GCD[#! - 1, 2^# + 1] > 1 &] (* G. C. Greubel, Oct 15 2018 *)
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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..1230], n->Gcd(Factorial(n)-1, 2^n+1)>1); # Muniru A Asiru, Oct 16 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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