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 A028236 If n = Product (p_j^k_j), a(n) = numerator of Sum 1/p_j^k_j. 7
 1, 1, 1, 1, 1, 5, 1, 1, 1, 7, 1, 7, 1, 9, 8, 1, 1, 11, 1, 9, 10, 13, 1, 11, 1, 15, 1, 11, 1, 31, 1, 1, 14, 19, 12, 13, 1, 21, 16, 13, 1, 41, 1, 15, 14, 25, 1, 19, 1, 27, 20, 17, 1, 29, 16, 15, 22, 31, 1, 47, 1, 33, 16, 1, 18, 61, 1, 21, 26, 59, 1, 17, 1, 39, 28, 23, 18, 71, 1, 21, 1, 43 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS Klaus Brockhaus, Table of n, a(n) for n = 1..10000 FORMULA Fraction is additive with a(p^e) = 1/p^e. a(n) = Sum_{k=1..A001221(n)} n/a141809(n,k). - Reinhard Zumkeller, Nov 10 2013 PROG (MAGMA) a028236:=func< k | k eq 1 select 1 else Numerator(&+[ f[i, 1]^-f[i, 2]: i in [1..#f] ]) where f is Factorization(k) >; [ a028236(n):n in [1..82] ]; // Klaus Brockhaus, Nov 06 2010 (Haskell) a028236 n = sum \$ map (div n) \$ a141809_row n -- Reinhard Zumkeller, Nov 10 2013 CROSSREFS Denominator is n (A000027). Sequence in context: A250097 A340678 A028235 * A066504 A292771 A322837 Adjacent sequences:  A028233 A028234 A028235 * A028237 A028238 A028239 KEYWORD nonn,easy,frac AUTHOR EXTENSIONS More terms from Erich Friedman STATUS approved

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Last modified April 10 14:07 EDT 2021. Contains 342845 sequences. (Running on oeis4.)