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 A166306 Denominator of Bernoulli_n multiplied by the sum of the associated inverse primes in the Staudt-Clausen theorem, n=1, 2, 4, 6, 8, 10,... 1
 1, 5, 31, 41, 31, 61, 3421, 5, 557, 821, 371, 121, 3421, 5, 929, 15745, 557, 5, 2557843, 5, 15541, 1805, 743, 241, 60887, 61, 1673, 821, 929, 301, 79085411, 5, 557, 66961, 31, 4397, 188641729, 5, 31, 3281, 277727, 421, 4462547, 5, 66817, 313477, 1487, 5, 5952449, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS This is the absolute value of the sum of the negative terms in row n of triangle A165908. It appears that a(n) mod 9 is always one of {1, 2, 4, 5, 7, 8}. Apparently a(n) = A027761(n+1) for n>=1. - Joerg Arndt, May 06 2012 LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 EXAMPLE The primes associated with B_10 = 5/66 are 2, 3 and 11. 66*(1/2+1/3+1/11) = 33+22+6 = 61 is the representative in this sequence. MATHEMATICA a146[n_] := Sum[ Boole[ PrimeQ[d+1]]/(d+1), {d, Divisors[2n]}] + BernoulliB[2n]; primes[n_] := Select[ Prime /@ Range[n+1], Divisible[2n, #-1]&]; row[n_] := With[{pp = primes[n]}, Join[{a146[n]}, -1/pp]*Times @@ pp]; a[n_] := -Total[ Select[ row[n-1] // Rest, Negative]]; Table[a[n], {n, 1, 50}] (* Jean-François Alcover, Aug 09 2012 *) CROSSREFS Cf. A080092, A002445, A165226. Sequence in context: A042837 A162173 A027761 * A341632 A287300 A162665 Adjacent sequences:  A166303 A166304 A166305 * A166307 A166308 A166309 KEYWORD nonn AUTHOR Paul Curtz, Oct 11 2009 EXTENSIONS Edited and extended by R. J. Mathar, Jul 08 2011 Extended to 50 terms by Jean-François Alcover, Aug 09 2012 STATUS approved

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Last modified June 13 06:38 EDT 2021. Contains 344981 sequences. (Running on oeis4.)