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 A198805 #22 Feb 06 2024 08:10:26 %S A198805 1,0,0,30,0,360,7650,0,302400,4544400,11226600,324324000,4310633250, %T A198805 24324300000,437404968000,5634178329780,45972927000000, %U A198805 697866761592000,8962716395833200,88725951057744000,1258898645656852200 %N A198805 Number of closed paths of length n whose steps are 15th roots of unity, U_15(n). %C A198805 U_15(n), (comment in article): For each m >= 1, the sequence (U_m(N)), N >= 0 is P-recursive but is not algebraic when m > 2. %H A198805 Gilbert Labelle and Annie Lacasse, <a href="https://doi.org/10.46298/dmtcs.2937">Closed paths whose steps are roots of unity</a>, in FPSAC 2011, Reykjavik, Iceland DMTCS proc. AO, 2011, 599-610. %Y A198805 Cf. A198808, A321418. %K A198805 nonn %O A198805 0,4 %A A198805 _Simon Plouffe_, Oct 30 2011