A172418 Numbers k that have measure of smoothness J larger than 3, where J = log(k)/log(rad(k)) and rad(k) is the product of the distinct prime divisors of k (A007947).

16, 32, 64, 81, 128, 243, 256, 288, 324, 384, 432, 486, 512, 576, 625, 648, 729, 768, 864, 972, 1024, 1152, 1250, 1280, 1296, 1458, 1536, 1600, 1728, 1944, 2000, 2048, 2187, 2304, 2401, 2500, 2560, 2592, 2916, 3072, 3125, 3136, 3200, 3456, 3584, 3645

Offset: 1

Author

Artur Jasinski, Feb 02 2010

Keywords

• nonn

Comments

Subsequence of A049094.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A007947, A049094, A059172, A172419, A172420, A172421, A172422.

Programs

Mathematica

aa = {}; Do[kk = FactorInteger[c]; nn = 1; Do[nn = nn*kk[[n]][[1]], {n, 1, Length[kk]}]; If[Log[c]/Log[nn] > 3, AppendTo[aa, c]], {c, 2, 10000}]; aa