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 A235938 #19 Jan 05 2019 01:35:23 %S A235938 0,0,0,0,2,4,22,124,816,6112,51642,485604,5034606,57080204,702766384, %T A235938 9339630016,133281949954,2033044422948,33014191980502,568686463073484, %U A235938 10357838456504880 %N A235938 Number of circular permutations with exactly one specified increasing or decreasing modular run (3-sequence), with clockwise and counterclockwise traversals counted as distinct. %D A235938 Paul J. Campbell, Circular permutations with exactly one modular run (3-sequence), submitted to Journal of Integer Sequences %H A235938 Wayne M. Dymáček and Isaac Lambert, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL14/Dymacek/dymacek5.html">Circular permutations avoiding runs of i, i+1, i+2 or i, i-1, i-2</a>, Journal of Integer Sequences, Vol. 14 (2011) Article 11.1.6. %F A235938 a(n) = 2*A235937(n). %e A235938 With specified sequence 123: %e A235938 a(5) = 2: 12354, 32154. %e A235938 a(6) = 4: 123564, 321564, 123645, 321546. %Y A235938 Cf. A165961, A165964, A165962, A078628, A078673. %Y A235938 Cf. A235937, A235939, A235940, A235941, A235942, A235943. %K A235938 nonn %O A235938 1,5 %A A235938 _Paul J. Campbell_, Jan 20 2014, with Joe Marasco and Ashish Vikram %E A235938 a(20)-a(21) from _Alois P. Heinz_, Jan 24 2014 %E A235938 Obsolete b-file deleted by _N. J. A. Sloane_, Jan 05 2019