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A131605 Perfect powers of nonprimes (m^k where m is a nonprime positive integer and k >= 2). 10

%I #14 Oct 09 2013 01:58:18

%S 1,36,100,144,196,216,225,324,400,441,484,576,676,784,900,1000,1089,

%T 1156,1225,1296,1444,1521,1600,1728,1764,1936,2025,2116,2304,2500,

%U 2601,2704,2744,2916,3025,3136,3249,3364,3375,3600,3844,3969,4225,4356,4624

%N Perfect powers of nonprimes (m^k where m is a nonprime positive integer and k >= 2).

%C Although 1 is a square, is a cube, and so on..., 1 is sometimes excluded from perfect powers since it is not a well-defined power of 1 (1 = 1^k for any k in [2, 3, 4, 5, ...])

%H Daniel Forgues, <a href="/A131605/b131605.txt">Table of n, a(n) for n=1..8649</a>

%o (PARI) isok(n) = if (n == 1, return (1), return (ispower(n, ,&np) && (! isprime(np)))); \\ _Michel Marcus_, Jun 12 2013

%Y Cf. A000961, A001597, A024619, A025475.

%K nonn

%O 1,2

%A _Daniel Forgues_, May 27 2008

%E _Klaus Brockhaus_ previously provided a table of n, a(n) for n=1..1323, May 28 2008

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Last modified March 28 08:02 EDT 2024. Contains 371236 sequences. (Running on oeis4.)