219781

Appears in sequences

• Strong pseudoprimes to base 7.at n=30A020233
• Strong pseudoprimes to base 15.at n=24A020241
• Strong pseudoprimes to base 28.at n=34A020254
• Strong pseudoprimes to base 37.at n=36A020263
• Pseudoprimes to bases 2 and 7.at n=14A083733
• Pseudoprimes whose prime factors do not divide any smaller pseudoprime.at n=11A084653
• Brilliant Sarrus numbers.at n=18A086837
• Composite k such that Fibonacci(k) == Legendre(k,5) == 1 (mod k).at n=32A093372
• Composite n such that n divides both Fibonacci(n-1) and Fibonacci(n) - 1.at n=21A094401
• Semiprimes k that divide Fibonacci(k-1).at n=26A177086
• Frobenius pseudoprimes with respect to Fibonacci polynomial x^2 - x - 1.at n=25A212424
• Composite numbers k such that k divides Fibonacci(k+1) or Fibonacci(k-1) and 2^(k-1) == 1 (mod k).at n=4A214434
• Fermat pseudoprimes to base 2 of the form (n^2 + 2*n)/3.at n=13A216170
• Composite integers k such that 2^k == 2 (mod k*(k+1)).at n=29A217465
• Octagonal numbers (A000567) which are also centered pentagonal numbers (A005891).at n=2A253923
• Octagonal numbers (A000567) that are semiprimes (A001358).at n=26A259677
• Odd numbers k > 1 such that 2^((k-1)/2) == -(2/k) = -A091337(k) (mod k), where (2/k) is the Jacobi (or Kronecker) symbol.at n=12A306310
• Frobenius pseudoprimes == 1,4 (mod 5) with respect to Fibonacci polynomial x^2 - x - 1.at n=18A319168
• Fermat pseudoprimes to base 2 that are octagonal.at n=13A321868
• Numbers that are both Fermat pseudoprimes to base 2 (A001567) and Bruckman-Lucas pseudoprimes (A005845).at n=1A329240