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 A124809 #17 Sep 08 2022 08:45:28 %S A124809 50,325,1025,1445,1682,1850,3250,4625,4901,6725,8650,9802,11450,13690, %T A124809 13925,17425,20450,24650,28225,33125,37250,42850,47525,53825,57122, %U A124809 59050,63002,66050,71825,79525,85850,94250,101125,106930,110225,117650 %N A124809 Numbers of the form (square + 1) that are not squarefree. %C A124809 The sequence is infinite (see comment in A049532). - _Emmanuel Vantieghem_, Oct 25 2016 %H A124809 Harvey P. Dale, <a href="/A124809/b124809.txt">Table of n, a(n) for n = 1..1000</a> %F A124809 a(n) = A049532(n)^2 + 1. %t A124809 Select[Range[400]^2+1,!SquareFreeQ[#]&] (* _Harvey P. Dale_, Sep 15 2016 *) %o A124809 (Magma) [n^2+1: n in [1..500]| not IsSquarefree(n^2+1)]; // _Vincenzo Librandi_, Oct 26 2016 %o A124809 (PARI) is(n)=issquare(n-1) && !issquarefree(n) \\ _Charles R Greathouse IV_, Nov 05 2017 %Y A124809 Cf. A002522, A013929, A049532, A069987. %K A124809 nonn %O A124809 1,1 %A A124809 _Reinhard Zumkeller_, Nov 08 2006