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 A061464 #16 Mar 02 2025 23:48:25
%S A061464 1,1,4,108,6912,21600000,583200000,480290277600000,
%T A061464 31476303632793600000,16727798278915463577600000,
%U A061464 52274369621610823680000000000,14914487726878692033020558868480000000000
%N A061464 Denominator of 1/(1^1) + 1/(2^2) + 1/(3^3) + ... 1/(n^n).
%F A061464 A061463(n)/a(n) = Integral_{x=0..1} Gamma(n, -x*log(x))/(x^x*Gamma(n)) dx. - _Thomas Scheuerle_, Feb 26 2025
%e A061464 1, 5/4, 139/108, 8923/6912,...
%p A061464 summ := 0; for n from 1 to 15 do printf("%d ", denom(summ)); if (1 = 1) then summ := summ + 1/n^n: end if; od;
%t A061464 Join[{1},Denominator/@Table[Sum[1/i^i,{i,n}],{n,12}]] (* _Harvey P. Dale_, Jul 03 2011 *)
%o A061464 (PARI) a(n) = denominator(sum(k=1, n, 1/(k^k))) \\ _Thomas Scheuerle_, Feb 26 2025
%Y A061464 Cf. A061463, A073009.
%K A061464 nonn,frac,easy
%O A061464 0,3
%A A061464 _Amarnath Murthy_, May 04 2001
%E A061464 More terms from Winston C. Yang (winston(AT)cs.wisc.edu), May 19 2001
%E A061464 a(12) from _Harvey P. Dale_, Jul 03 2011