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A201816
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Numbers k such that 90*k + 13 is prime.
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16
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0, 1, 2, 3, 4, 5, 7, 8, 9, 12, 16, 17, 19, 22, 23, 30, 31, 35, 36, 37, 38, 40, 42, 46, 47, 49, 50, 51, 53, 58, 59, 60, 61, 63, 66, 67, 68, 74, 75, 80, 82, 84, 86, 88, 92, 95, 99, 100, 101, 103, 105, 107, 108, 112, 114, 116, 119, 121, 122, 123, 124, 126, 127
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OFFSET
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1,3
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COMMENTS
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Looking at the format 90*k+13 modulo 9 and modulo 10 we see that all entries of A142318 have digital root 4 and last digit 3. (Reverting the process is an application of the Chinese remainder theorem.)
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LINKS
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MAPLE
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a:= proc(n) option remember; local k;
for k from 1+ `if`(n=1, -1, a(n-1))
while not isprime(90*k+13) do od; k
end:
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MATHEMATICA
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PROG
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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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STATUS
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approved
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