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%I #3 Mar 30 2012 17:22:33
%S 1,5,45,585,9945,69615,348075,10094175,111035925,4108329225,
%T 168441498225,56147166075,393030162525,20830598613825,395781373662675,
%U 24142663793423175,24142663793423175,555281267248733025
%N Denominator of 1 + 1/5 + 1/9 +...+ 1/(4n+1).
%C The first 11 terms are the same as the least common multiples in A051539.
%t Table[Denominator[Total[1/Range[1, 4n+1, 4]]], {n, 0, 20}]
%Y Cf. A016813 (4n+1), A075136 (numerators), A051539 (lcm of 5, 9, 13, ..., 4n+1).
%K easy,frac,nonn
%O 0,2
%A _T. D. Noe_, Aug 04 2004