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 A088377 #15 May 16 2025 07:27:17 %S A088377 1,4,9,4,25,4,49,4,9,4,121,4,169,4,9,4,289,4,361,4,9,4,529,4,25,4,9,4, %T A088377 841,4,961,4,9,4,25,4,1369,4,9,4,1681,4,1849,4,9,4,2209,4,49,4,9,4, %U A088377 2809,4,25,4,9,4,3481,4,3721,4,9,4,25,4,4489,4,9,4,5041,4,5329,4,9,4 %N A088377 a(n) = (smallest prime factor of n)^2; a(1) = 1. %H A088377 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LeastPrimeFactor.html">Least Prime Factor</a>. %H A088377 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SquareNumber.html">Square Number</a>. %F A088377 a(n) = A000290(A020639(n)). %F A088377 a(n) = sqrt(A088379(n)). - _Amiram Eldar_, May 16 2025 %t A088377 a[n_] := FactorInteger[n][[1, 1]]^2; Array[a, 100] (* _Amiram Eldar_, May 16 2025 *) %o A088377 (PARI) a(n) = if(n == 1, 1, factor(n)[1,1]^2); \\ _Amiram Eldar_, May 16 2025 %Y A088377 Cf. A000290, A068319, A088378, A088379, A247180. %K A088377 nonn,easy %O A088377 1,2 %A A088377 _Reinhard Zumkeller_, Sep 28 2003