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%I #23 May 10 2021 04:37:30
%S 8,13,20,24,29,33,40,44,48,53,57,61,68,72,76,80,85,89,93,97,104,108,
%T 112,116,120,125,129,133,137,141,148,152,156,160,164,168,173,177,181,
%U 185,189,193,200,204,208,212,216,220,224,229,233,237,241,245,249,253,260,264,268,272,276,280
%N Numbers k such that the distance to the largest square less than k is a multiple of 4.
%C A071797(a(n)) = 4*m, A053186(a(n)+1) = 4*m, m > 0.
%C Apparently a bisection of A079896. While it may not be difficult to prove that the sequence is a subsequence of A079896, the apparent fact that a(n) = A079896(2n-1) is by no means obvious.
%H Harvey P. Dale, <a href="/A227453/b227453.txt">Table of n, a(n) for n = 1..1000</a>
%e 8 - 2^2 = 1*4 and 24 - 4^2 = 2*4 so 8 and 24 are in the sequence.
%t lsm4Q[n_]:=Module[{s=Floor[Sqrt[n]]^2},s<n&&Divisible[n-s,4]]; Select[ Range[300],lsm4Q] (* _Harvey P. Dale_, Jun 20 2014 *)
%o (PARI) is(n)=(n-sqrtint(n-1)^2)%4==0
%Y Cf. A048760, A053186, A071797, A079896.
%K nonn
%O 1,1
%A _Ralf Stephan_, Sep 22 2013
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