OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..100
FORMULA
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)).
MATHEMATICA
q[x_] = (Sqrt[2/Pi]*Sqrt[x])/ (E^(x/2)*Erf[Sqrt[x]/Sqrt[2]]) ;
Denominator[CoefficientList[Series[q[x], {x, 0, 30}], x]]
(* program improved by Bob Hanlon (hanlonr(AT)cox.net) *)
PROG
(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
(Sage)
def A154289_list(len):
R, C = [1], [1]+[0]*(len-1)
for n in (1..len-1):
for k in range(n, 0, -1):
C[k] = C[k-1] / (2*k+1)
C[0] = -sum(C[k] for k in (1..n))
R.append((C[0]).denominator())
return R
print(A154289_list(17)) # Peter Luschny, Feb 21 2016
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Roger L. Bagula, Jan 06 2009
EXTENSIONS
Edited by Michel Marcus and Joerg Arndt, Apr 30 2013
STATUS
approved