A144862 Composite numbers n such that sqrt(n) > f(n), where f(n) = 2 * rad(n) if 4 divides n and rad(n) otherwise.

27, 32, 54, 64, 81, 125, 128, 162, 192, 216, 243, 250, 256, 288, 324, 343, 375, 384, 405, 432, 486, 500, 512, 567, 576, 625, 640, 648, 675, 686, 729, 768, 800, 864, 896, 972, 1000, 1024, 1029, 1125, 1152, 1215, 1250, 1280, 1296, 1323, 1331, 1350, 1372, 1458

Offset: 1

Author

Reikku Kulon, Sep 23 2008

Keywords

• easy
• nonn

Comments

Subset of A144100.

Crossrefs

Cf. A000040, A007947, A144100.

Programs

PARI

rad(n) = local(p); p=factor(n)[, 1]; prod(i=1, length(p), p[i]) ;
ff(n) = if ((n % 4)==0 , 2*rad(n), rad(n)); isok(n) = (n != 1) && (! isprime(n)) && (n > ff(n)^2); \\ Michel Marcus, Aug 09 2013