This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A101418 #9 Feb 16 2025 08:32:55
%S A101418 1,4,11,19,30,44,60,78,99,122,148,176,207,240,276,314,354,397,443,491,
%T A101418 541,594,649,707,767,830,895,963,1033,1105,1180,1257,1337,1419,1504,
%U A101418 1591,1681,1773,1868,1965,2064,2166,2271,2378,2487,2599,2713,2830,2949
%N A101418 Floor of the area of a lens constructed using circular arcs of radius n.
%H A101418 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Lens.html">Lens</a>
%F A101418 a(n) = floor((4*Pi - 3*sqrt(3))/6*n^2).
%e A101418 a(2) = 4 because a lens given by the intersection of two circles of radius two has an area of approximately 4.91347...
%t A101418 Table[Floor[(4*Pi - 3*Sqrt[3])/6*r^2], {r, 1, 60}]
%o A101418 (PARI) a(n)=(4*Pi-sqrt(27))*n^2\6 \\ _Charles R Greathouse IV_, Nov 27 2016
%Y A101418 Cf. A093731.
%K A101418 nonn
%O A101418 1,2
%A A101418 Joseph Biberstine (jrbibers(AT)indiana.edu), Jan 16 2005