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 A386009 #13 Jul 20 2025 17:11:27
%S A386009 1,5,4,9,2,5,1,0,4,3,4,2,5,6,3,4,0,4,8,4,0,0,5,4,4,0,2,8,1,5,8,9,4,3,
%T A386009 5,5,5,3,0,8,8,3,5,2,6,7,0,1,5,8,3,6,8,5,4,7,2,3,3,4,6,6,4,9,5,4,7,2,
%U A386009 2,4,6,5,2,1,8,3,3,4,7,1,6,1,9,4,2
%N A386009 Decimal expansion of Product_{k>=2} k^( ((k/2)^(k-1)) / (exp(k/2)*k!) ).
%C A386009 The geometric mean of the Borel distribution with parameter value 1/2 (A386016) approaches this constant. In general, for parameter value p it approaches Product_{k>=2} k^(((p*k)^(k-1))/((e^(p*k))*k!)).
%F A386009 Equals exp( Sum_{k>=2} log(k) * (((k/2)^(k-1)) / (exp(k/2)*k!)) ).
%e A386009 1.549251043425634048400544028158943555...
%t A386009 Exp[NSum[((k/2)^(k-1) * Log[k])/(E^(k/2) * Factorial[k]), {k, 2, Infinity}, WorkingPrecision -> 120, NSumTerms -> 1000]]
%Y A386009 Cf. A386016.
%K A386009 nonn,cons
%O A386009 1,2
%A A386009 _Jwalin Bhatt_, Jul 14 2025