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 A120061 #7 Dec 03 2018 15:37:29
%S A120061 1,3,384,7044820107264000,
%T A120061 43717045185341789547924740349079734434493871700606561180430383632613376000000000000000000000000000000000
%N A120061 Number of universal cycles for permutations of n objects.
%C A120061 A universal cycle of permutations is a cycle of n! digits such that each permutation of {1,...,n} occurs exactly once as a block of n-1 consecutive digits (with its redundant final element suppressed). a(4)=2^7*3, a(5)=2^33*3^8*5^3, a(6)=2^190*3^49*5^33, a(7)=2^1217*3^123*5^119*7^5*11^28*43^35*73^20*79^21*109^35 ~=1.582284037*10^747.
%D A120061 D. E. Knuth, The Art of Computer Programming, Volume 4, Fascicle 2, Generating All Tuples and Permutations. Ch. 7.2.1.2, Exercises 111 and 112, Page 75 and Answer to Exercise 112, pages 120-121.
%H A120061 Dawn Curtis, Taylor Hines, Glenn Hurlbert, Tatiana Moyer, <a href="https://arxiv.org/abs/0809.3725">Near universal cycles for subsets exist</a>, arXiv:0809.3725 [math.CO], 22 Sep 2008, arXiv:0809.3725v1 [math.co] 3 November 2018.
%H A120061 Brad W. Jackson, <a href="https://doi.org/10.1016/0012-365X(93)90330-V">Universal cycles of k-subsets and k-permutations</a>, Discrete Math. 117 (1993), no. 1-3, 141-150.
%e A120061 (121323) is a universal cycle of permutations for n=3,
%e A120061 (123124132134214324314234) is one for n=4.
%Y A120061 Cf. A005563.
%K A120061 nonn
%O A120061 2,2
%A A120061 _Hugo Pfoertner_, Jun 06 2006