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 A057008 #17 May 19 2022 17:44:39 %S A057008 1,31,1361,334576,207009649,268530771271,644969015852641, %T A057008 2642258726261312896,17337468317813249073281, %U A057008 173383832437017181584973783,2538593496477071922439308897841,52641334467700181691498204296713016,1503509056221581488501100896035227575441 %N A057008 Number of conjugacy classes of subgroups of index n in free group of rank 5. %D A057008 R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.13(c), pp. 76, 112. %H A057008 J. H. Kwak and J. Lee, <a href="https://doi.org/10.1002/(SICI)1097-0118(199610)23:2<105::AID-JGT1>3.0.CO;2-X">Enumeration of connected graph coverings</a>, J. Graph Th., 23 (1996), 105-109. %H A057008 J. H. Kwak and J. Lee, <a href="https://web.archive.org/web/20061002144237/http://com2mac.postech.ac.kr/Lecture/Lec-1.pdf">Enumeration of graph coverings and surface branched coverings</a>, Lecture Note Series 1 (2001), Com^2MaC-KOSEF, Korea. See chapter 3. %H A057008 V. A. Liskovets, <a href="https://doi.org/10.1023/A:1005950823566">Reductive enumeration under mutually orthogonal group actions</a>, Acta Applic. Math., 52 (1998), 91-120. %Y A057008 Cf. A057004-A057013. %Y A057008 Inverse Euler transform of A160447. %K A057008 nonn %O A057008 1,2 %A A057008 _N. J. A. Sloane_, Sep 09 2000 %E A057008 More terms from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 25 2001