A167184 Smallest prime power >= n that is not prime.

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

Offset

1,2

Links

Robert Price, Table of n, a(n) for n = 1..2000

Example

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.

Mathematica

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 *)

Prog

(PARI) isA025475(n) = (omega(n) == 1 & !isprime(n)) || (n == 1)
A167184(n) = {local(m); m=n; while(!isA025475(m), m++); m}

Crossrefs

List of nonprime prime powers: A025475.

Previous nonprime prime power: A167185.

Next prime power including primes: A000015.

Sequence in context: A105352 A132200 A110757 * A276113 A232406 A322040

Adjacent sequences: A167181 A167182 A167183 * A167185 A167186 A167187

Keyword

easy,nonn

Author

Michael B. Porter, Oct 29 2009

Status

approved