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 A211306 Numerator of Sum_{k=1..n} 1/lambda(k), where  lambda(k) is the Carmichael's lambda function. 2
 1, 2, 5, 3, 13, 15, 47, 53, 55, 29, 74, 163, 331, 341, 89, 371, 1499, 513, 4657, 4837, 4957, 5029, 55679, 59639, 12007, 12139, 12227, 12491, 87833, 90605, 454873, 461803, 467347, 117703, 59429, 30292, 121553, 122323, 61739, 126943, 254579, 259199, 259859 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 EXAMPLE 1, 2, 5/2, 3, 13/4, 15/4, 47/12, 53/12, 55/12, 29/6, 74/15, 163/30, ... MAPLE with(numtheory): a:=n->numer(sum(1/lambda(k), k=1..n)): seq(a(n), n=1..50); MATHEMATICA Numerator[Table[Sum[1/CarmichaelLambda[k], {k, 1, n}], {n, 1, 50}]] Numerator @ Accumulate @ Table[1 / CarmichaelLambda[n], {n, 1, 50}] (* Amiram Eldar, Sep 19 2019 *) CROSSREFS Cf. A002322, A028415, A212716 (denominator). Sequence in context: A091265 A262373 A028415 * A267101 A035334 A243506 Adjacent sequences:  A211303 A211304 A211305 * A211307 A211308 A211309 KEYWORD nonn,frac AUTHOR Michel Lagneau, May 25 2012 STATUS approved

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Last modified September 27 20:35 EDT 2020. Contains 337388 sequences. (Running on oeis4.)