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 A119251 #18 Aug 15 2023 17:02:51 %S A119251 2,3,5,7,11,12,13,17,18,19,20,23,24,28,29,31,37,40,41,43,44,45,47,48, %T A119251 50,52,53,54,56,59,61,63,67,68,71,73,75,76,79,80,83,88,89,92,96,97,98, %U A119251 99,101,103,104,107,109,112,113,116,117,124,127,131,135,136,137,139,147 %N A119251 Positive integers each with exactly 1 unitary prime divisor (i.e., n is included if and only if A056169(n) = 1). %C A119251 Also, numbers expressible as the product of a prime and a powerful number not divisible by that prime. - _Franklin T. Adams-Watters_, Jul 25 2006 %H A119251 Amiram Eldar, <a href="/A119251/b119251.txt">Table of n, a(n) for n = 1..10000</a> %e A119251 28 has the prime factorization of 2^2 * 7^1. 28 is therefore included in this sequence because there is exactly one prime raised to an exponent of 1 in 28's prime factorization. %t A119251 Select[Range@147, Count[FactorInteger@#, 1, 2] == 1 &] (* _Robert G. Wilson v_, Jul 25 2006 *) %Y A119251 Cf. A001694, A056169. %K A119251 nonn %O A119251 1,1 %A A119251 _Leroy Quet_, Jul 23 2006 %E A119251 More terms from _Robert G. Wilson v_ and _Franklin T. Adams-Watters_, Jul 25 2006