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 A298612 #32 Mar 01 2018 05:36:19
%S A298612 0,1,3,8,14,29,53,100,180,343,623,1172,2182,4105,7701,14590,27584,
%T A298612 52475,99867,190732,364710,699237,1342169,2581412,4971052,9587563,
%U A298612 18512775,35792550,69273650,134219777,260301157,505294108,981706812
%N A298612 The number of concave polygon classes.
%C A298612 A concave polygon has at least one concave interior corner angle, and at least three convex interior corner angles. Two concave polygon classes are equivalent if the cyclic ordering of the concave and convex interior angles of each are equal.
%C A298612 a(n) is also the number of combinatorial necklaces with n beads in 2 colors (black and white) with at least one white bead and no fewer than 3 black beads.
%H A298612 Jason Davies, <a href="https://www.jasondavies.com/necklaces/">Combinatorial necklaces and bracelets</a>
%H A298612 Peter Kagey, <a href="/A298612/a298612.pdf">Illustrations of a(4), a(5), a(6)</a>
%F A298612 a(n) = A000031(n) - A004526(n) - 3, n >= 3.
%F A298612 a(n) = A262232(n)-1, n >= 3.
%t A298612 Table[DivisorSum[n, EulerPhi[#] 2^(n/#) &]/n - Floor[n/2] - 3, {n, 3, 35}] (* _Michael De Vlieger_, Jan 28 2018 *)
%Y A298612 Cf. A000031, A004526, A227910, A262232.
%K A298612 nonn
%O A298612 3,3
%A A298612 _Stuart E Anderson_, Jan 23 2018