21227

Properties

Appears in sequences

• Sum of 12 positive 9th powers.at n=16A004801
• Number of ordered 5-tuples of integers from [ 2,n ] with no common factors among triples.at n=21A015657
• Primes that remain prime through 2 iterations of function f(x) = 8x + 1.at n=38A023260
• Discriminants of quintic fields with 2 complex conjugates (negated).at n=36A023684
• A triangle sequence based on a prime root product using a primorial function: f(n)=primorial(n); p(x,n)=If[n == 0, 1, f(n)*(x + 1/f(n))*Product[x + Prime[i], {i, 1, n - 1}]]; t(n,m)=coefficients(p(x,n)).at n=18A142583
• Primes congruent to 46 mod 59.at n=38A142773
• Primes congruent to 60 mod 61.at n=35A142858
• Prime numbers where the last digit is the sum of all the previous digits.at n=31A156617
• Primes of the form 2*k^2 + 9.at n=39A201476
• Primes of the form p^2 + 2q^2 with p and q odd primes.at n=31A201613
• Number of n-bead necklaces labeled with numbers -7..7 allowing reversal, with sum zero and three times sum of squares <= n*(7)*(7+1).at n=5A208804
• Number of (n+1) X (2+1) 0..1 arrays with nondecreasing max(x(i,j),x(i,j-1)) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.at n=8A250577
• T(n,k)=Number of (n+1)X(k+1) 0..1 arrays with nondecreasing max(x(i,j),x(i,j-1)) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.at n=46A250583
• Number of (n+1) X (4+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries.at n=10A251145
• Primes p such that p = q^2 + 2*r^2 where q and r are also primes.at n=32A260553
• Primes having only {1, 2, 7} as digits.at n=40A260889
• Primes that can be generated by the concatenation in base 3, in descending order, of two consecutive integers read in base 10.at n=26A287301
• a(n) is the first prime p such that A329308(p) = n.at n=50A329309
• Primes p such that p^5 - 1 has 8 divisors.at n=23A341665
• Prime numbersat n=2387