%I #17 Sep 07 2022 09:51:47
%S 1,2,4,14,48,162,826,3558,17296,101714,529014,3218118,21014010,
%T 140974654,888205714,6529087674,52806013456,375280736754,
%U 2994842092102,23821110274230,217847892367318,1894959770821614,16188955616322394,142246084665611010,1376483692715941594
%N "EGJ" (unordered, element, labeled) transform of 2,2,2,2...
%C From _Peter Bala_, Sep 05 2022: (Start)
%C Conjecture: the Gauss congruences a(n*p^k) == a(n*p^(k-1)) (mod p^k) hold for all primes p and positive integers n and k. Cf. A007837.
%C Equivalently, the expansion of exp( Sum_{n >= 1} a(n)^x^n/n ) = 1 + 2*x + 4*x^2 + 10*x^3 + 28*x^4 + 82*x^5 + 293*x^6 + ... has integer coefficients. Cf. A168268. (End)
%H Andrew Howroyd, <a href="/A032312/b032312.txt">Table of n, a(n) for n = 0..200</a>
%H C. G. Bower, <a href="/transforms2.html">Transforms (2)</a>
%F E.g.f: Product_{k > 0} (1 + x^k/k!)^2. - _Andrew Howroyd_, Sep 11 2018
%t With[{nn=30},CoefficientList[Series[Product[(1+x^k/k!)^2,{k,nn}],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Feb 07 2019 *)
%o (PARI) seq(n)={Vec(serlaplace(prod(k=1, n, (1 + x^k/k! + O(x*x^n))^2)))} \\ _Andrew Howroyd_, Sep 11 2018
%Y Cf. A007837, A168268.
%K nonn
%O 0,2
%A _Christian G. Bower_
%E a(0)=1 prepended and terms a(22) and beyond from _Andrew Howroyd_, Sep 11 2018