%I #9 Apr 30 2023 02:09:05
%S 7,5,9,2,2,3,1,0,1,8,5,1,6,0,3,7,7,9,5,7,7,7,5,9,0,4,4,9,5,5,8,4,5,5,
%T 9,5,9,1,3,3,5,2,4,0,2,1,8,4,4,8,1,9,8,3,6,0,9,5,2,0,8,1,4,5,5,5,0,3,
%U 7,8,6,2,2,8,6,4,0,9,4,5,3,7,4,7,6,6,7,6,9,7,6,7,3,9,5,3,9,8,2,7,7,7,6,5,6,1,4,7,4,1,8,8,0,8,5
%N Decimal expansion of 1 / 1^1 - 1 / (1^1 * 2^2) + 1 / (1^1 * 2^2 * 3^3) - 1 / (1^1 * 2^2 * 3^3 * 4^4) + ...
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Hyperfactorial.html">Hyperfactorial</a>.
%e 0.759223101851603779577759044955845595913352402184...
%t With[{m = 105}, RealDigits[N[Sum[(-1)^(n + 1)/Hyperfactorial[n], {n, 1, Infinity}], m + 2], 10, m][[1]]] (* _Amiram Eldar_, Apr 30 2023 *)
%Y Cf. A000312, A002109, A068996, A073009, A083648, A137986, A287013, A347345.
%K nonn,cons
%O 0,1
%A _Ilya Gutkovskiy_, Aug 28 2021