20639

Properties

Appears in sequences

• Incorrect duplicate of A297408.at n=20A007355
• Number of partitions satisfying (cn(0,5) <= cn(2,5) and cn(0,5) <= cn(3,5) and cn(0,5) <= cn(1,5) and cn(0,5) <= cn(4,5)).at n=40A036801
• Primes such that the sum of the factorials of the digits is a perfect square.at n=33A052279
• Primes of form Sum_{k=1..n} (prime(k)+1).at n=35A062736
• Prime(n) and prime(n+4) use the same digits.at n=19A069796
• Primes p such that googol - p is prime.at n=11A108252
• Lesser of a twin-prime pair where both are expressible as the sum of two triangular numbers.at n=39A118638
• Primes congruent to 21 mod 61.at n=39A142819
• Primes that can be generated by the concatenation in base 7, in descending order, of two consecutive integers read in base 10.at n=18A287309
• Primes p such that p+2 is prime and p+A001414(p+1)+(p+2) is prime.at n=40A330488
• a(0) = 1; a(n) = Sum_{k=0..floor(n/4)} binomial(n-3*k,k) * a(k).at n=30A352041
• Primes p, not safe primes, such that the smallest factor of (2^(p-1)-1) / 3 is equal to p.at n=25A360827
• Primes that are no longer prime if in their binary representation any single bit is flipped but stay prime if a 1 bit is prepended.at n=36A385245
• Prime numbersat n=2326