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 A292103 #5 Sep 14 2017 15:07:31 %S A292103 0,0,0,1,5,15,35,70,123,195,285,420,586,818,1110,1451,1846,2361,2956, %T A292103 3704,4567,5530,6631,7963,9443,11113,13005,15111,17450,20167,23064, %U A292103 26396,30053,34046,38447,43230,48245,53890,60061,66703,73713,81503,89746 %N A292103 Number of points that are the intersections of exactly two semicircles in the configuration A290447(n). %C A292103 No formula or recurrence is known. %C A292103 Needs a b-file (A290867 gives first 100 terms). %Y A292103 Cf. A290447, A292104. %Y A292103 Column k=2 of triangle in A290867. %K A292103 nonn %O A292103 1,5 %A A292103 _N. J. A. Sloane_, Sep 14 2017