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 A376931 #22 Nov 22 2024 11:12:03 %S A376931 0,0,1,0,2,2,3,0,5,4,5,4,6,6,9,0,8,10,9,8,13,10,11,8,14,12,16,12,14, %T A376931 18,15,0,21,16,23,20,18,18,25,16,20,26,21,20,33,22,23,16,27,28,33,24, %U A376931 26,32,37,24,37,28,29,36,30,30,47,0,44,42,33,32,45,46,35 %N A376931 Number of points out of n points placed on a circle that can never be reached when starting at one point and then moving clockwise in incrementally increasing steps (first 1, then 2, 3, 4, ...). %C A376931 Put n distinct points on the edge of a circle. Connect the first to the point 1 step clockwise from it, then connect that one to the point 2 steps clockwise from that, continuing with 3 steps, 4 steps, etc. In the end, a(n) is the number of points never landed on. %F A376931 a(n) = n - A117484(n). %Y A376931 Cf. A117484. %K A376931 nonn %O A376931 1,5 %A A376931 _Payton Richards_, Oct 11 2024