20663

Properties

Appears in sequences

• Primes that remain prime through 3 iterations of function f(x) = 5x + 4.at n=30A023284
• Recip transform of 2*(1 + x^6)-1/(1-x).at n=8A049160
• a(n) is smallest safe prime (A005385) such that a(n) + 12*n is the next safe prime, i.e., x = (a(n) - 1)/2 and x + 6*n are closest Sophie Germain primes.at n=32A059327
• Safe primes (A005385) (p and (p-1)/2 are primes) such that 12*p+1 is also prime.at n=47A075707
• a(n) = numerator of sum of reciprocals of the terms of the continued fraction for H(n) = Sum_{k=1..n} 1/k.at n=23A112286
• Prime numbers, isolated from neighboring primes by >16.at n=22A137875
• Primes congruent to 13 mod 59.at n=40A142740
• Primes congruent to 45 mod 61.at n=37A142843
• Primes with a prime number of partitions into prime parts.at n=27A146949
• Odd primes of the form (1+n)*(2+2*n)+n*(3+2*n) = 4*n^2+7*n+2.at n=21A171749
• Primes which are the sum of three distinct positive cubes in two or more distinct ways.at n=15A180088
• Numbers m such that m, m-1, m-2 and m-3 are 1,2,3,4-almost primes respectively.at n=30A201220
• Primes of the form 3*m^2 - 4.at n=21A201716
• Primes of the form 10n^2 - 90n + 163.at n=27A256376
• Number of nX3 0..2 arrays with every element equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) (1,-1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.at n=4A277783
• Number of nX5 0..2 arrays with every element equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) (1,-1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.at n=2A277785
• T(n,k)=Number of nXk 0..2 arrays with every element equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) (1,-1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.at n=23A277788
• T(n,k)=Number of nXk 0..2 arrays with every element equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) (1,-1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.at n=25A277788
• a(n) is the smallest prime p such that p^2 divides Bell(p+n) - Bell(n+1) - Bell(n).at n=5A286664
• The least k for which A335884(k) = n.at n=13A335883