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 A072980 Numerator of b(n)=sum (k'<=n,1/k') where k' denotes the squarefree numbers. 2
 1, 3, 11, 11, 61, 11, 82, 82, 82, 171, 1951, 1951, 26133, 13424, 41273, 41273, 716656, 716656, 13871719, 13871719, 4700888, 9548741, 222854273, 222854273, 222854273, 112857219, 112857219, 112857219, 3310041496, 20075905417 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS b(n) was used by Niven in the 70's for an alternative proof of the divergence of the sum of reciprocal of primes. LINKS Table of n, a(n) for n=1..30. 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) = numerator(sum(k=1, n, issquarefree(k)/k)); \\ Michel Marcus, Nov 28 2013 CROSSREFS Cf. A072983. Sequence in context: A248410 A059200 A232038 * A128500 A365037 A043051 Adjacent sequences: A072977 A072978 A072979 * A072981 A072982 A072983 KEYWORD easy,frac,nonn AUTHOR Benoit Cloitre, Aug 21 2002 STATUS approved

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Last modified December 10 16:12 EST 2023. Contains 367713 sequences. (Running on oeis4.)