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 A321418 #10 Nov 10 2018 14:19:18 %S A321418 1,0,0,5,0,3,15,0,15,35,6,45,70,30,105,135,90,210,255,210,390,465,420, %T A321418 690,810,771,1170,1345,1335,1905,2153,2205,2985,3345,3495,4536,5060, %U A321418 5340,6720,7465,7920,9735,10755,11460,13815,15180,16230,19230,21045,22545 %N A321418 Number of n element multisets of the 15th roots of unity with zero sum. %C A321418 Equivalently, the number of closed convex paths of length n whose steps are the 15th roots of unity up to translation. %H A321418 Andrew Howroyd, <a href="/A321418/b321418.txt">Table of n, a(n) for n = 0..1000</a> %F A321418 G.f.: (1 - x^15)/((1 - x^3)^5 * (1 - x^5)^3). %o A321418 (PARI) Vec((1 - x^15)/((1 - x^3)^5 * (1 - x^5)^3) + O(x^50)) %Y A321418 Cf. A198805, A321419. %K A321418 nonn,easy %O A321418 0,4 %A A321418 _Andrew Howroyd_, Nov 09 2018