38828domain: NAppears in sequencesE.g.f. satisfies: A(x) = x - log(1-A(x))*log(1+A(x)).at n=5A214759Numbers k such that P = 2^k - 1 - Sum_{primes p<k} 2^(p-1) is prime.at n=27A215891a(n) = Sum_{k=1..n} mu(gcd(n, k)) * lcm(n, k) / gcd(n, k).at n=42A332658