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A204657
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Numbers n such that n!10 + 2 is prime.
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14
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0, 1, 3, 5, 9, 11, 13, 19, 21, 25, 41, 57, 79, 127, 135, 149, 165, 177, 193, 209, 223, 255, 273, 287, 297, 375, 433, 459, 481, 565, 1079, 1435, 1543, 1771, 1913, 1983, 2063, 2305, 2653, 6789, 8757, 11149, 13671, 15433, 16369, 17261, 18129, 22129, 22785, 22875, 25235, 25247, 26329, 27675, 33391, 39075, 41195, 47435, 47621, 48409, 59235, 59715, 61571, 65433, 78761, 83033
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OFFSET
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1,3
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COMMENTS
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n!10 = Product_{k=0..floor((n-1)/10)}(n - 10k).
The first 11 primes associated with this sequence: 3, 3, 5, 7, 11, 13, 41, 173, 233, 1877, 293603. - Robert Price, Mar 10 2017
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LINKS
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Nathan Russell, n!10+2 results, message 23995 in primenumbers Yahoo group, Jan 17, 2012.
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MATHEMATICA
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MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 10] + 2] &]
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PROG
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(PARI) for(n=0, 9999, isprime(prod(i=0, (n-2)\10, n-10*i)+2)& print1(n", "))
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CROSSREFS
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Cf. A204658, A204659, A204660, A204661, A204662, A204663, A204664, A156165, A156167, A085150, A085148, A085146, A037083, A080778, A002981.
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KEYWORD
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nonn,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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