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 A324217 #23 Jun 02 2025 17:24:08
%S A324217 0,1,50,933,12465,119906,864705,4930446,23280925,94308983,336704397,
%T A324217 1081565510,3176476119,8638660038,21978039571,52745266132,
%U A324217 120228555981,261785061087,547126506745,1102086250237,2147107495684
%N A324217 Number of connected 2n-regular loopless multigraphs on seven unlabeled nodes.
%C A324217 There are no (2n+1)-regular graphs satisfying the condition above.
%C A324217 Multigraphs are loopless.
%C A324217 Initial terms computed with 'nauty and Traces' (see the link).
%H A324217 Brendan McKay and Adolfo Piperno, <a href="http://pallini.di.uniroma1.it">nauty and Traces</a>
%o A324217 (nauty) for ((n=0;n<30;n=n+2)); do geng -c -d1 7 -q | multig -r${n} -u; done
%Y A324217 Row n=7 of A328682.
%Y A324217 Cf. A324218.
%K A324217 nonn,more,hard
%O A324217 0,3
%A A324217 _Natan Arie Consigli_, Apr 30 2019
%E A324217 a(10)-a(20) from _Andrew Howroyd_, Mar 17 2020