1129909

Appears in sequences

• a(n) = 8*a(n-1) + 21*a(n-2), with a(1)=1, a(2)=11.at n=6A094703
• Numbers k, excluding primes and squares of primes, such that gcd(k, numerator of H(k-1)) > 1, where the harmonic number H(j) = Sum_{i=1..j} 1/i.at n=10A228810