59987

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 31 ones.at n=26A031799
• n-th 4k+1 prime times n-th 4k-1 prime.at n=25A048630
• Solutions to phi(x + omega(x)) = phi(x) + d(x), where phi() = A000010(), d() = A000005() and omega() = A001221().at n=9A063868
• Numbers k such that A065608(k) = A065608(k+2).at n=20A065064
• Numbers k such that k and k+2 have the same number (A000005) and sum of divisors (A000203).at n=17A229254
• Composite numbers k such that if k = a U b (where U denotes concatenation) then a' + b' = k', where a', b' and k' are the arithmetic derivatives of a, b and k.at n=13A239724
• Semiprimes sp such that sp plus its digit sum is a perfect square.at n=40A244733
• Numbers k such that the sum of the numbers from 1 to k and that from 1 to k+1 share the same sum of divisors.at n=29A375819
• Numbers k such that s(k) = s(k+2), where s(k) is the sum of odd divisors of k (A000593).at n=17A387920