24653

Appears in sequences

• Numbers k such that 99*2^k+1 is prime.at n=41A032399
• Numbers n such that phi(reverse(n)) = phi(reverse(n-1)) + phi(reverse(n-2)).at n=23A069969
• Let p = n-th odd prime. Then a(n) = least positive integer congruent to 5 modulo 8 such that Legendre(a(n), q) = -1 for all odd primes q <= p.at n=8A094847
• Records in A094847.at n=6A094849
• Write n-th semiprime in binary, sum as if decimal numbers.at n=7A122467
• Numbers n where tau(n) and n-tau(n) are perfect squares, with tau(n) the number of divisors of n (A000005).at n=41A245197
• Number of nX7 0..2 arrays with no element equal to more than one of its king-move neighbors and with new values introduced in order 0 sequentially upwards.at n=11A280858
• a(n) = prime(1)^2 + prime(n)^2.at n=36A287922
• Semiprimes of the form k^2 + 4.at n=35A360741