This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A137257 #14 Jun 24 2022 05:27:25
%S A137257 4,12,16,18,20,24,27,28,36,44,48,50,52,54,60,64,68,72,76,80,84,90,92,
%T A137257 98,100,108,112,116,120,124,126,132,135,140,144,148,150,156,160,162,
%U A137257 164,168,172,176,180,188,189,192,196,198,200,204,208,212,216,220,228,234
%N A137257 A number k is included if there is at least one (nonzero) exponent in the prime factorization of k that is not coprime to k.
%C A137257 The number of terms not exceeding 10^m, for m = 1, 2, ..., are 1, 25, 254, 2567, 25730, 257286, 2572950, 25729433, 257294360, 2572944786, ... . Apparently, the asymptotic density of this sequence exists and equals 0.257294... . - _Amiram Eldar_, Jun 24 2022
%H A137257 Amiram Eldar, <a href="/A137257/b137257.txt">Table of n, a(n) for n = 1..10000</a>
%e A137257 48 = 2^4 * 3^1; so the exponents in the prime factorization of 48 are 4 and 1. 48 is not coprime to 4; therefore 48 is included in this sequence.
%t A137257 Select[Range[3000], GCD[ #, Product[FactorInteger[ # ][[i, 2]], {i, 1, Length[FactorInteger[ # ]]}]] > 1 &] (* _Stefan Steinerberger_, Mar 16 2008 *)
%K A137257 nonn
%O A137257 1,1
%A A137257 _Leroy Quet_, Mar 11 2008
%E A137257 More terms from _Stefan Steinerberger_, Mar 16 2008