login
a(n) = floor(Pi*(n + sqrt(2))^2).
1

%I #21 Sep 08 2022 08:46:20

%S 0,6,18,36,61,92,129,172,222,278,340,409,484,565,652,746,846,952,1065,

%T 1184,1309,1440,1578,1722,1872,2029,2191,2361,2536,2718,2906,3100,

%U 3300,3507,3720,3940,4165,4397,4635,4880,5131,5388,5651,5921,6197,6479,6767,7062

%N a(n) = floor(Pi*(n + sqrt(2))^2).

%C a(n) > A000328(n+1) for every n >= 0.

%H G. C. Greubel, <a href="/A295026/b295026.txt">Table of n, a(n) for n = -1..5000</a>

%p seq(floor(Pi*(n+sqrt(2))^2),n=-1..46); # _Muniru A Asiru_, Oct 11 2018

%t f[n_] := Floor[Pi (n + Sqrt@2)^2]; Array[f, 47, -1] (* _Robert G. Wilson v_, Dec 12 2017 *)

%o (PARI) a(n)=floor(Pi*(n+sqrt(2))^2)

%o (Magma) R:=RealField(10); [Floor(Pi(R)*(n+Sqrt(2))^2): n in [-1..50]]; // _G. C. Greubel_, Oct 10 2018

%Y Cf. A000328.

%K nonn,easy

%O -1,2

%A _Arkadiusz Wesolowski_, Nov 12 2017