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 A241591 #11 Jan 19 2017 23:29:55 %S A241591 1,1,1,3,3,5,45,315,35,567,14175,1925,467775,868725,7007,638512875, %T A241591 638512875,14889875,97692469875,14849255421,28868125,17717861581875, %U A241591 2143861251406875,2505147019375,236682282155319,284473896821296875,814172781296875,3784415134680984375 %N A241591 Denominators of Postnikov's hook-length formula 2^n*(n+1)^(n-1)/n!. %D A241591 Alexander Postnikov. Permutohedra, associahedra, and beyond. in: Conference in Honor of Richard Stanley's Sixtieth Birthday, June 2004. International Mathematics Research Notices, 6:1026-1106, 2009. %H A241591 Matthew Wilson, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v21i2p20">Bruhat order on fixed-point-free involutions in the symmetric group</a>, Electron. J. Combin., 21(2) (2014), #P2.20. %e A241591 1, 2, 6, 64/3, 250/3, 1728/5, 67228/45, 2097152/315, 1062882/35, 80000000/567, 9431790764/14175, 6115295232/1925, 7168641576148/467775, ... %p A241591 t1:= [seq(2^n*(n+1)^(n-1)/n!,n=0..50)]: %p A241591 t2:=map(numer, t1); # A241590 %p A241591 t3:=map(denom, t1); # A241591 %o A241591 (PARI) vector(30, n, n--; denominator(2^n*(n+1)^(n-1)/n!)) \\ _Michel Marcus_, Jul 18 2015 %Y A241591 Cf. A241590. %Y A241591 Has same start as A248592 but is a different sequence. %K A241591 nonn,frac %O A241591 0,4 %A A241591 _N. J. A. Sloane_, May 13 2014