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A153170
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Numbers k such that 3*k + 2 is not prime.
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8
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2, 4, 6, 8, 10, 11, 12, 14, 16, 18, 20, 21, 22, 24, 25, 26, 28, 30, 31, 32, 34, 36, 38, 39, 40, 41, 42, 44, 46, 47, 48, 50, 51, 52, 53, 54, 56, 58, 60, 61, 62, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 76, 78, 80, 81, 82, 84, 86, 88, 90, 91, 92, 94, 95, 96, 98, 99, 100, 101, 102
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OFFSET
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1,1
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COMMENTS
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Numbers k such that (3*k)!/(3*k + 2) is an integer. - Peter Bala, Jan 25 2017
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LINKS
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EXAMPLE
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Distribution of the odd terms in the following triangular array:
*;
*, *;
*, 11, *;
*, *, *, *;
*, *, 25, *, *;
*, 21, *, *, 47, *;
*, *, *, *, *, *, *;
*, *, 39, *, *, 73, *, *;
*, 31, *, *, 69, *, *, 107, *;
*, *, *, *, *, *, *, *, *, *;
*, *, 53, *, *, 99, *, *, 145, *, *;
*, 41, *, *, 91, *, *, 141, *, *, 191, *;
etc., where * marks the noninteger values of (4*h*k + 2*k + 2*h - 1)/3 with h >= k >= 1. - Vincenzo Librandi, Jan 15 2013
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MAPLE
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for n from 0 to 100 do
if irem(factorial(3*n), 3*n+2) = 0 then print(n); end if;
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MATHEMATICA
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PROG
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(PARI) for(n=1, 200, if(!isprime(3*n+2), print1(n, ", "))) \\ Joerg Arndt, Nov 27 2010
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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