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
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