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A072983 Denominator of b(n)=sum (k'<=n,1/k') where k' denotes the squarefree numbers. 2
1, 2, 6, 6, 30, 5, 35, 35, 35, 70, 770, 770, 10010, 5005, 15015, 15015, 255255, 255255, 4849845, 4849845, 1616615, 3233230, 74364290, 74364290, 74364290, 37182145, 37182145, 37182145, 1078282205, 6469693230, 200560490130, 200560490130 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
b(n) was used by Niven in the 1970's for an alternative proof of the divergence of the sum of reciprocals of the primes.
LINKS
Ivan Niven, A Proof of the Divergence of sum 1/p, The American Mathematical Monthly, Vol. 78, No. 3 (Mar., 1971), pp. 272-273.
PROG
(PARI) a(n)=denominator(sum(k=1, n, issquarefree(k)/k))
CROSSREFS
Cf. A072980.
Sequence in context: A087310 A130087 A085087 * A055204 A212397 A008339
KEYWORD
easy,frac,nonn
AUTHOR
Benoit Cloitre, Aug 21 2002
STATUS
approved

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Last modified March 3 00:46 EST 2024. Contains 370499 sequences. (Running on oeis4.)