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%I #9 Aug 04 2020 11:41:44
%S 0,4,12,22,34,47,62,78,95,113,132,153,174,196,219,243,268,294,320,347,
%T 375,403,432,462,492,524,555,588,621,654,688,723,758,794,830,867,905,
%U 943,981,1020,1060,1100,1140,1181,1223,1264,1307,1350,1393,1437,1481
%N Nearest integer to (4/3)*Pi*n^(3/2).
%C Approximates the volume of the ball { (x,y,z) | x^2+y^2+z^2 < n }. Provides a more refined scale than A002101(n) = a(n^2).
%t Table[Round[4/3*Pi* n^(3/2)],{n,0,50}] (* _Harvey P. Dale_, Aug 04 2020 *)
%o (PARI) a(n)=round(4/3*Pi*n^1.5)
%Y Cf. A000092 and references therein.
%K nonn
%O 0,2
%A _M. F. Hasler_, Mar 26 2012
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