cp's OEIS Frontend

A106827 Numerators in expansion of (1 - x)^(-1/x) / e.

%I A106827 #11 May 16 2023 10:52:50
%S A106827 1,1,11,315,17129,1510425,196385475,35327367075,8399994587985,
%T A106827 2550903574364145,963207568455370875,442613044315692124875,
%U A106827 243195136160954426677305,157442856285298191126143625,118607799383105394973766029875,102867257381973743111023517821875
%N A106827 Numerators in expansion of (1 - x)^(-1/x) / e.
%D A106827 L. Comtet, Analyse Combinatoire, P. U. F., 1970, tome second, p. 140, #12.
%D A106827 L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 293, Problem 11.
%D A106827 S. R. Finch, Mathematical Constants, Cambridge, 2003, Section 1 . 3 . 1.
%H A106827 G. C. Greubel, <a href="/A106827/b106827.txt">Table of n, a(n) for n = 0..201</a>
%F A106827 Sum_{n>=0} a(n)/(2n)!*x^n = (1 - x)^(-1/x) / e.
%F A106827 a(n) = A055505(n)*(2n)! / A055535(n).
%F A106827 a(n) = (-1)^n * Sum_{k=0..n} Stirling1(n+k, k) * !(n-k) * C(2*n, n+k), where !n = A000166(n) is the subfactorial, C(n,k) are binomial coefficients. - _Vladimir Reshetnikov_, Sep 23 2016
%F A106827 a(n) = (2*n)! * coefficients of Product_{j >= 2} exp(x^(j-1)/j). - _G. C. Greubel_, Sep 14 2021
%e A106827 G.f. = 1 + 1*x/2! + 11*x^2/4! + 315*x^3/6! + 17129*x^4/8! + 503475*x^5/10! + ...
%t A106827 Table[(-1)^n Sum[StirlingS1[n+k, k] Subfactorial[n-k] Binomial[2n, n+k], {k, 0, n}], {n, 0, 20}] (* _Vladimir Reshetnikov_, Sep 23 2016 *)
%t A106827 With[{m=30}, CoefficientList[Series[(1-x)^(-1/x)/E, {x,0,m}], x]*(2*Range[0,m])!] (* _G. C. Greubel_, Sep 14 2021 *)
%o A106827 (Magma) m:=31; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( (&*[Exp(x^(j-1)/j): j in [2..40]]) )); [Factorial(2*n-2)*b[n]: n in [1..m]]; // _G. C. Greubel_, Sep 14 2021
%o A106827 (Sage)
%o A106827 def A_list(prec):
%o A106827     P.<x> = PowerSeriesRing(QQ, prec)
%o A106827     return P( product(exp(x^(j-1)/j) for j in (2..41)) ).list()
%o A106827 A=A_list(40)
%o A106827 [factorial(2*n)*A[n] for n in (0..31)] # _G. C. Greubel_, Sep 14 2021
%Y A106827 Cf. A055505, A055535.
%K A106827 nonn,frac
%O A106827 0,3
%A A106827 _Philippe Deléham_, May 21 2005
%E A106827 a(5) corrected by _G. C. Greubel_, Sep 14 2021