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 A012254 #8 Dec 21 2013 22:37:14 %S A012254 1,1,1,2,5,24,109,720,4521,40320,330681,3628800,36468717,479001600, %T A012254 5721101541,87178291200,1205289090513,20922789888000,328897528901361, %U A012254 6402373705728000,112769846051251797,2432902008176640000 %N A012254 exp(arcsinh(arctanh(x)))=1+x+1/2!*x^2+2/3!*x^3+5/4!*x^4+24/5!*x^5... %F A012254 E.g.f.: Q(0)-1, where Q(k) = 2 + arctanh(x)/(1 - arctanh(x)/Q(k+1) ); (continued fraction). - _Sergei N. Gladkovskii_, Dec 19 2013 %Y A012254 Bisections are A010050 and |A012091|. %K A012254 nonn %O A012254 0,4 %A A012254 Patrick Demichel (patrick.demichel(AT)hp.com)