20551

Properties

Appears in sequences

• Primes of the form n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2 + (n+4)^2 + (n+5)^2.at n=17A027867
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 92 ones.at n=11A031860
• Prime lucky numbers k (from A031157) such that nextprime(k)=nextlucky(k).at n=27A057698
• Prime numbers occurring at integer Pythagorean distance (radius) from 1 in Ulam square prime-spiral. Primes on axes are excluded.at n=29A078765
• Primes in which the unit place digit is 1 and the k-th most significant digit is prime (2,3,5,7) if k is prime else is composite (4,6,8,9,0).at n=28A089704
• Smallest of 3 consecutive prime numbers such that p1*p2*p3*d1*d2=average of twin prime pairs; p1,p2,p3 consecutive prime numbers; d1(delta)=p2-p1, d2(delta)=p3-p2.at n=18A153409
• Greatest number m such that the fractional part of (4/3)^A154131(n) <= 1/m.at n=6A154135
• Numbers k such that (19^k - 4^k)/15 is prime.at n=8A228076
• Primes p such that p-2 and q are primes, where q is concatenation of binary representations of p and p-2: q = p * 2^L + p-2, where L is the length of binary representation of p-2: L=A070939(p-2).at n=29A232237
• Lesser of consecutive primes whose sum is a palindromic number.at n=24A242386
• Primes p such that q = p^2 + 10 and q^2 + 10 are also prime.at n=26A243368
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 169", based on the 5-celled von Neumann neighborhood.at n=14A279547
• a(n) is the smallest prime p such that there is a multiplicative subgroup H of Z/pZ, of odd size and of index 2n, such that for any two cosets H1 and H2 of H, H1 + H2 contains all of (Z/pZ)\0.at n=24A282001
• a(1) = 2; a(n + 1) = smallest prime > a(n) such that a(n + 1) - a(n) is the product of 7 primes.at n=33A285692
• a(n) = [x^n] (1/(1 - x/(1 - x^2/(1 - x^3/(1 - x^4/(1 - x^5/(1 - ...)))))))^n, a continued fraction.at n=8A291653
• Primes p such that p mod A001414(p-1) = p mod A001414(p+1).at n=47A339180
• Primes p such that q = p mod A001414(p-1) = p mod A001414(p+1) is prime.at n=26A339182
• Prime numbersat n=2320