16485763

Appears in sequences

• Smallest nonnegative integer k such that k^2 + 1 has exactly n distinct prime factors.at n=10A180278
• Numbers n such that n^2+1 can be expressed as j^2+k^2, j>k>1, gcd(j,k)=1, in more ways than for any smaller n.at n=7A300167
• a(n) is the smallest k such that tau(k^2 + 1) is equal to 2^n, where tau = A000005 and a(n) = -1 if no such k exists.at n=10A380969