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A130034
Denominators of partial sums of a series for the inverse of the arithmetic-geometric mean (agM) of 1 and sqrt(2)/2.
3
1, 8, 256, 2048, 262144, 2097152, 67108864, 536870912, 274877906944, 2199023255552, 70368744177664, 562949953421312, 72057594037927936, 576460752303423488, 18446744073709551616, 147573952589676412928
OFFSET
0,2
COMMENTS
See the references and the W. Lang link under A129934.
LINKS
FORMULA
a(n) = denom(sum((((2*j)!/(j!^2))^2)*(1/2^(5*j)),j=0..n)), n>=0.
MATHEMATICA
Denominator[Table[Sum[(((2*k)!/(k!^2))^2)*(1/2^(5*k)), {k, 0, n}], {n, 0, 50}]] (* G. C. Greubel, Aug 17 2018 *)
PROG
(PARI) for(n=0, 50, print1(denominator(sum(k=0, n, (((2*k)!/(k!^2))^2)*(1/2^(5*k)))), ", ")) \\ G. C. Greubel, Aug 17 2018
CROSSREFS
Sequence in context: A300176 A372670 A291850 * A128787 A013824 A010044
KEYWORD
nonn,frac,easy
AUTHOR
Wolfdieter Lang Jun 01 2007
STATUS
approved