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a(n) = 4*n - floor(2*n*sqrt(2)).
1

%I #19 Sep 08 2022 08:45:59

%S 0,2,3,4,5,6,8,9,10,11,12,13,15,16,17,18,19,20,22,23,24,25,26,27,29,

%T 30,31,32,33,34,36,37,38,39,40,42,43,44,45,46,47,49,50,51,52,53,54,56,

%U 57,58,59,60,61,63,64,65,66,67,68,70,71,72,73,74,75,77,78,79,80

%N a(n) = 4*n - floor(2*n*sqrt(2)).

%H Vincenzo Librandi, <a href="/A195178/b195178.txt">Table of n, a(n) for n = 0..10000</a>

%F a(n) = A008586(n) - A022842(n). - _Michel Marcus_, Oct 31 2017

%t With[{c=2Sqrt[2]},Table[4n-Floor[c n],{n,0,90}]] (* _Harvey P. Dale_, Sep 17 2011 *)

%o (Magma) [4*n-Floor(2*n*(Sqrt(2))): n in [0..70]]; // _Vincenzo Librandi_, Sep 12 2011

%o (PARI) for(n=0,50, print1(4*n - floor(2*n*sqrt(2)), ", ")) \\ _G. C. Greubel_, Oct 30 2017

%Y Cf. A008586, A022842.

%K nonn

%O 0,2

%A _Clark Kimberling_, Sep 10 2011