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 A287621 #8 May 30 2017 00:19:27 %S A287621 1,2,3,18,5,6,7,450,24,10,11,150,13,14,15,22050,17,192,19,90,21,22,23, %T A287621 7350,160,26,3000,126,29,30,31,2668050,33,34,35,4800,37,38,39,4410,41, %U A287621 42,43,198,120,46,47,705600,896,1440,51,234,53,24000,55,3150,57,58 %N A287621 a(n) = least k such that A287620(k) = n. %C A287621 a(n) >= n. %C A287621 a(n) = n iff n is squarefree (A005117). %C A287621 If n = p_1 * ... * p_k where p_1, ..., p_k are prime, then a(n) <= prime(1)^p_1 * ... * prime(k)^p_k. %H A287621 Rémy Sigrist, <a href="/A287621/a287621.pdf">Illustration of the first terms</a> %e A287621 See illustrations of the first terms in Links section. %Y A287621 Cf. A005117, A287620. %K A287621 nonn %O A287621 1,2 %A A287621 _Rémy Sigrist_, May 28 2017