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%I #37 Mar 07 2020 08:51:25
%S 1,3,45,945,14175,93555,638512875,273648375,44405668125,
%T 194896477400625,32157918771103125,201717854109646875,
%U 3028793579456347828125,698952364489926421875,564653660170076273671875,5660878804669082674070015625,7217620475953080409439269921875
%N Denominators of coefficients in expansion of 1/ ( Sum_{n>=1} ( x^(n - 1)/(2*n - 1)!! ) ).
%H G. C. Greubel, <a href="/A154289/b154289.txt">Table of n, a(n) for n = 0..100</a>
%F G.f.: 1/( Sum_{n>=1}( x^(n - 1)/(2*n - 1)!! ) ) = sqrt(2/Pi) * sqrt(x))/ (exp(x/2) * erf(sqrt(x)/sqrt(2)).
%t q[x_] = (Sqrt[2/Pi]*Sqrt[x])/ (E^(x/2)*Erf[Sqrt[x]/Sqrt[2]]) ;
%t Denominator[CoefficientList[Series[q[x], {x, 0, 30}], x]]
%t (* program improved by Bob Hanlon (hanlonr(AT)cox.net) *)
%o (PARI) lista(n) = { n++; x = z + z*O(z^n); P = 1/sum(m=1, n, (x^(m - 1)/prod(k=1, m, 2*k-1))); n--; for (i=0, n, print1(denominator(polcoeff(P, i, z)), ", " ););} \\ _Michel Marcus_, Apr 30 2013
%o (Sage)
%o def A154289_list(len):
%o R, C = [1], [1]+[0]*(len-1)
%o for n in (1..len-1):
%o for k in range(n, 0, -1):
%o C[k] = C[k-1] / (2*k+1)
%o C[0] = -sum(C[k] for k in (1..n))
%o R.append((C[0]).denominator())
%o return R
%o print(A154289_list(17)) # _Peter Luschny_, Feb 21 2016
%Y Cf. A154288.
%K nonn,frac
%O 0,2
%A _Roger L. Bagula_, Jan 06 2009
%E Edited by _Michel Marcus_ and _Joerg Arndt_, Apr 30 2013
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