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%I #8 Jun 10 2016 01:22:59
%S 1,4,3,48,40,1440,1260,8960,72576,7257600,6652800,958003200,889574400,
%T 11623772160,163459296000,41845579776000,39520825344000,
%U 12804747411456000,12164510040883200,231704953159680000,4644631106519040000
%N Numerator of (2*(n+1)!/(n+2)).
%C The moments, i.e. E(X^n) = int(x^n * p(x), x = 0..infinity) for n > 0, of the probability density function p(x) = 2*x*E(x, 1, 1), see A163931, lead to this sequence.
%H J. W. Meijer and N. H. G. Baken, <a href="http://dx.doi.org/10.1016/0167-7152(87)90041-1">The Exponential Integral Distribution</a>, Statistics and Probability Letters, Volume 5, No.3, April 1987. pp 209-211.
%F a(n) = numer(2*(n+1)!/(n+2))
%F a(n) = (n+1) * A090586(n+1)
%F a(2*n) = A110468(n) and a(2*n+1) = (2*n)!*A085250(n+1)/A128060(n+2).
%e The first few moments of p(x) are: 1, 4/3, 3, 48/5, 40, 1440/7, … .
%p a := proc(n): numer(2*(n+1)!/(n+2)) end: seq(a(n), n=0..20);
%o (PARI) a(n) = numerator(2*(n+1)!/(n+2)) \\ _Felix Fröhlich_, Jun 09 2016
%Y Cf. A090585 (denominators), A090586, A085250, A110468, A128059, A128060, A163931.
%K nonn,frac,easy
%O 0,2
%A _Johannes W. Meijer_, Jun 08 2016
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