300420

Appears in sequences

• a(n) = (1/n^2) * Sum_{d|n} moebius(n/d)*binomial(3*d,d).at n=9A268617
• Primitive terms of A388022: numbers k that satisfy sigma(k) AND 3*k = 3*k, but none of whose proper divisors satisfy the same condition.at n=41A388025