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 A304180 #13 Feb 16 2025 08:33:54
%S A304180 1,2,3,4,5,3,7,8,9,5,11,9,13,7,5,16,17,9,19,25,7,11,23,27,25,13,27,49,
%T A304180 29,5,31,32,11,17,7,9,37,19,13,125,41,7,43,121,25,23,47,81,49,25,17,
%U A304180 169,53,27,11,343,19,29,59,25,61,31,49,64,13,11,67,289,23,7,71,27,73,37,25
%N A304180 If n = Product (p_j^k_j) then a(n) = max{p_j}^max{k_j}.
%H A304180 Ilya Gutkovskiy, <a href="/A304180/a304180.jpg">Scatter plot of a(n) up to n=100000</a>.
%H A304180 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GreatestPrimeFactor.html">Greatest Prime Factor</a>.
%H A304180 <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>.
%F A304180 a(n) = A006530(n)^A051903(n).
%F A304180 a(p^k) = p^k where p is a prime.
%F A304180 a(A005117(k)) = A073482(k).
%F A304180 a(A002110(k)) = A000040(k).
%e A304180 a(40) = 125 because 40 = 2^3*5^1, max{2,5} = 5, max{3,1} = 3 and 5^3 = 125.
%t A304180 Table[(FactorInteger[n][[-1, 1]])^(Max @@ Last /@ FactorInteger[n]), {n, 75}]
%o A304180 (PARI) a(n) = if(n == 1, 1, my(f = factor(n), p = f[, 1], e = f[, 2]); vecmax(p)^vecmax(e)); \\ _Amiram Eldar_, Sep 08 2024
%Y A304180 Cf. A000040, A000961 (fixed points), A002110, A005117, A006530, A034699, A051903, A053585, A073482, A081810, A304181.
%K A304180 nonn
%O A304180 1,2
%A A304180 _Ilya Gutkovskiy_, May 07 2018