30857

Appears in sequences

• Strong pseudoprimes to base 9.at n=29A020235
• Strong pseudoprimes to base 33.at n=12A020259
• Strong pseudoprimes to base 50.at n=18A020276
• Strong pseudoprimes to base 58.at n=23A020284
• Terms of A122780 which are not Carmichael numbers A002997.at n=39A153514
• a(n) = (3 + 2*n + 6*n^2 + 4*n^3)/3.at n=28A166464
• G.f.: x/exp( Sum_{n>=1} a(n)*x^n/n ) = Sum_{n>=1} moebius(n)*x^n.at n=18A195589
• Number of (7+2) X (n+2) 0..3 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=27A252726
• Euler pseudoprimes to base 3: composite integers such that abs(3^((n - 1)/2)) == 1 mod n.at n=23A262051
• Super pseudoprimes (or superpseudoprimes) to base 3: Fermat pseudoprimes to base 3 all of whose divisors that are larger than 1 are either primes or Fermat pseudoprimes to base 3.at n=19A328662
• a(n) = Sum_{k=1..n} (k/gcd(n, k))^3.at n=21A343513
• Odd pseudoprimes to base 3; composite terms of A271116.at n=39A351336
• Expansion of g.f. A(x) satisfying A(x) = 1 + x*A(x)/(1 - 2*x*A(x))^2.at n=7A365772
• Odd numbers k > 1 such that gcd(3,k) = 1 and 3^((k-1)/2) == -(3/k) (mod k), where (3/k) is the Jacobi symbol (or Kronecker symbol); Euler pseudoprimes to base 3 (A262051) that are not Euler-Jacobi pseudoprimes to base 3 (A048950).at n=3A375490