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A118055
Numerator of Sum_{i=1..n} 1/(s(i)^s(i)) where s(i) = i-th semiprime.
2
1, 733, 389546509, 15216660895232989, 165124648173861912289213141201, 516014525543318775927975356319557, 11473924061057077116469420939475877122177
OFFSET
1,2
COMMENTS
Semiprime analog of A117579. Fractions are 1/256, 733/186624, 389546509/99179645184, 15216660895232989/3874204890000000000, 165124648173861912289213141201/42041202325478752505760000000000, 516014525543318775927975356319557/131378757267121101580500000000000000, 11473924061057077116469420939475877122177 / 2921293509192991260690562210500000000000000, 239106294995420151295311285049507497083520504633431021289373163777 / 6087713879404511830817263262876196035025072.
FORMULA
a(n) = Numerator of Sum_{i=1..n} 1/(semiprime(i)^semiprime(i)).
a(n) = Numerator of Sum_{i=1..n} 1/(A001358(i)^A001358(i)).
a(n) = Numerator of Sum_{i=1..n} 1/A114850(n).
EXAMPLE
a(2) = 733 because (1/semiprime(1)^semiprime(1)) + (1/semiprime(2)^semiprime(2))
= (1/256) + (1/46656) = 733/186624.
MATHEMATICA
Numerator[Accumulate[1/#^#&/@Select[Range[25], PrimeOmega[#]==2&]]] (* Harvey P. Dale, Aug 09 2012 *)
CROSSREFS
Denominators = A118055. Cf. A001358, A051674, A114850, A117579.
Sequence in context: A220625 A260035 A033529 * A025356 A025348 A126556
KEYWORD
easy,frac,nonn
AUTHOR
Jonathan Vos Post, Apr 11 2006
STATUS
approved