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 A345248 #11 Apr 04 2022 06:33:25 %S A345248 1,1,4,28,302,4776,106732,3249352,131290812,6922560160,470586936176, %T A345248 40833342324864,4482709905772936,617622136930640128, %U A345248 106013904370382120400,22516967955697072408576,5880701545642715236590608,1877504184190590494772860928 %N A345248 Number of labeled connected simple graphs on n vertices without cycles of length 4. %C A345248 From _R. J. Mathar_, Apr 03 2022 (Start) %C A345248 The sequence contains the row sums of the number of labeled connected simple graphs on V vertices with E edges, the triangle with V>=0, E>=0: %C A345248 1 ; %C A345248 1 ; %C A345248 0 1; %C A345248 0 0 3 1; %C A345248 0 0 0 16 12; %C A345248 0 0 0 0 125 162 15; %C A345248 0 0 0 0 0 1296 2580 900; %C A345248 0 0 0 0 0 0 16807 47715 35595 6615 ; %C A345248 0 0 0 0 0 0 0 262144 1006488 1270080 619920 90720; %C A345248 0 0 0 0 0 0 0 0 4782969 23859108 44893170 39867660 15892065 1995840 ; %C A345248 (End) %Y A345248 LOG transform of A345249. %Y A345248 A077269 counts isomorphism classes. %Y A345248 Cf. A345218. %K A345248 nonn,hard %O A345248 1,3 %A A345248 _Brendan McKay_, Jun 12 2021