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 A227299 #24 Jul 23 2025 05:36:18
%S A227299 6,10,14,15,18,21,28,33,36,39,45,55,60,66,68,78,91,95,105,120,136,138,
%T A227299 150,153,171,189,190,203,210,231,248,253,264,276,300,315,325,333,351,
%U A227299 378,390,406,410,435,465,473,495,496,528,561,564,588,595,630,663,666,689,703,741,770,780,798,820,861,885
%N A227299 Number of vertices for which there is an alien in-magic directed star.
%C A227299 Numbers v such that there is an e in (v+1,2v-2) with s=(v+e)(v+e+1)/2v being an integer and c ceiling((2(v+e)-s)/2)=v-1.
%C A227299 This implies there exist an in-magic labeling of a directed star (K_{1,v-1}) containing two or more doubled edges (where a doubled edge is one in which there are two edges between a pair of vertices but the orientations of the two edges are distinct).
%C A227299 A graph with v vertices and e edges has an in-magic labeling if we label both the vertices and integers with the numbers 1, 2, ..., v+e using each number exactly once so that at any vertex, the sum of the vertex plus the sum of the labels on the incoming edges equals the same value for each vertex in the graph.
%C A227299 The first condition in our result is equivalent to sequence A024619. Thus, this is a subsequence of A024619. (Note: There are two such e for v=105).
%K A227299 nonn
%O A227299 1,1
%A A227299 _Alison Marr_, Jul 11 2013