21396

Appears in sequences

• Numbers k such that k^4 + 1, (k+2)^4 + 1 and (k+4)^4 + 1 are all primes.at n=19A073476
• Partial sums of A108019.at n=5A145730
• Number of amicable pairs with lesser member at most 2^n.at n=43A290985
• Numbers k such that F(k)*F(k+1) + F(k+2) is a prime, where F = A000045 (Fibonacci numbers).at n=31A305414