77939

Appears in sequences

• Number of 6-almost primes 6ap such that 2^n < 6ap <= 2^(n+1).at n=20A120037
• a(n) = Sum_{k=0..n-1} ( 1 + a(k) * a(n-k-1) ) for n >= 1, a(0) = 1.at n=9A305118