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 A124809 Numbers of the form (square + 1) that are not squarefree. 8

%I

%S 50,325,1025,1445,1682,1850,3250,4625,4901,6725,8650,9802,11450,13690,

%T 13925,17425,20450,24650,28225,33125,37250,42850,47525,53825,57122,

%U 59050,63002,66050,71825,79525,85850,94250,101125,106930,110225,117650

%N Numbers of the form (square + 1) that are not squarefree.

%C The sequence is infinite (see comment in A049532). - _Emmanuel Vantieghem_, Oct 25 2016

%H Harvey P. Dale, <a href="/A124809/b124809.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A049532(n)^2 + 1.

%t Select[Range[400]^2+1,!SquareFreeQ[#]&] (* _Harvey P. Dale_, Sep 15 2016 *)

%o (MAGMA) [n^2+1: n in [1..500]| not IsSquarefree(n^2+1)]; // _Vincenzo Librandi_, Oct 26 2016

%o (PARI) is(n)=issquare(n-1) && !issquarefree(n) \\ _Charles R Greathouse IV_, Nov 05 2017

%Y Cf. A002522, A013929, A049532, A069987.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Nov 08 2006

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Last modified June 4 17:50 EDT 2020. Contains 334828 sequences. (Running on oeis4.)