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A167184
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Smallest prime power >= n that is not prime.
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3
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1, 4, 4, 4, 8, 8, 8, 8, 9, 16, 16, 16, 16, 16, 16, 16, 25, 25, 25, 25, 25, 25, 25, 25, 25, 27, 27, 32, 32, 32, 32, 32, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 81, 81, 81, 81, 81, 81, 81, 81
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OFFSET
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1,2
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LINKS
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EXAMPLE
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For a(12), 12, 14, and 15 are not prime powers, and 13 is a prime power but it is prime. Since 16 = 2^4 is a prime power, a(12) = 16.
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MATHEMATICA
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Module[{ppwrs=Join[{1}, Sort[Flatten[Table[Prime[Range[5]]^p, {p, 2, 10}]]]]}, Flatten[ Table[Select[ppwrs, #>=n&, 1], {n, 90}]]] (* Harvey P. Dale, Oct 06 2014 *)
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PROG
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(PARI) isA025475(n) = (omega(n) == 1 & !isprime(n)) | (n == 1)
A167184(n) = {local(m); m=n; while(!isA025475(m), m++); m}
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CROSSREFS
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List of nonprime prime powers: A025475.
Previous nonprime prime power: A167185.
Next prime power including primes: A000015.
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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