73232344999domain: NAppears in sequencesDenominators a(n) of the fractions Sum_{n>=1} {(-1)^(n+1)*n/a(n)} = 1/a(1) - 2/a(2) + 3/a(3) - ... such that the sum has the concatenation of these denominators as decimal part. Case a(1) = 3.at n=3A320023