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 A273878 #8 Jun 10 2016 01:22:59 %S A273878 1,4,3,48,40,1440,1260,8960,72576,7257600,6652800,958003200,889574400, %T A273878 11623772160,163459296000,41845579776000,39520825344000, %U A273878 12804747411456000,12164510040883200,231704953159680000,4644631106519040000 %N A273878 Numerator of (2*(n+1)!/(n+2)). %C A273878 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 A273878 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 A273878 a(n) = numer(2*(n+1)!/(n+2)) %F A273878 a(n) = (n+1) * A090586(n+1) %F A273878 a(2*n) = A110468(n) and a(2*n+1) = (2*n)!*A085250(n+1)/A128060(n+2). %e A273878 The first few moments of p(x) are: 1, 4/3, 3, 48/5, 40, 1440/7, … . %p A273878 a := proc(n): numer(2*(n+1)!/(n+2)) end: seq(a(n), n=0..20); %o A273878 (PARI) a(n) = numerator(2*(n+1)!/(n+2)) \\ _Felix Fröhlich_, Jun 09 2016 %Y A273878 Cf. A090585 (denominators), A090586, A085250, A110468, A128059, A128060, A163931. %K A273878 nonn,frac,easy %O A273878 0,2 %A A273878 _Johannes W. Meijer_, Jun 08 2016