31697

Appears in sequences

• Sum{T(i,j)}, 0<=i<=n, 0<=j<=n, T given by A026659.at n=13A026668
• Number of 4 X 4 symmetric magic squares with line sum 2n.at n=14A093198
• Structured hexagonal diamond numbers (vertex structure 5).at n=28A100178
• Numbers m such that m^2 divides 2^k - 1 for some k, 0 < k <= m.at n=15A246503
• Euler pseudoprimes to base 3: composite integers such that abs(3^((n - 1)/2)) == 1 mod n.at n=25A262051
• The "residue" pseudoprimes: odd composite numbers n such that q(n)^((n-1)/2) == 1 (mod n), where base q(n) is the smallest prime quadratic residue modulo n.at n=22A307798
• Number of self-complementary set partitions of {1, ..., n} with no singletons.at n=15A324013
• 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=21A328662
• Numbers k such that the ring of integers of Q(2^(1/k)) is not Z[2^(1/k)].at n=37A342390
• 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=4A375490