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Denominators of partial sums of reciprocals of primorial numbers.
1

%I #5 Oct 15 2013 22:31:07

%S 2,3,10,105,770,15015,170170,4849845,6760390,3234846615,200560490130,

%T 72752334655,4680773285034,284407855036305,614889782588491410,

%U 465559406817000639,44715356980330526490,19548063559901161830545

%N Denominators of partial sums of reciprocals of primorial numbers.

%e n=5, Sum[1/q(j)],j=1..5 = 1/2+1/6+1/30+1/210+1/2310= (1155+385+77+11+1)/2310=1629/2310=543/770, a(5)=770

%t q[x_] := Apply[Times, Table[Prime[j], {j, 1, x}]] a(n)=Denominator[Apply[Plus, Table[1/q[w], {w, 1, n}]]]

%Y A002110.

%K frac,nonn

%O 1,1

%A _Labos Elemer_, Oct 04 2001