1141141

Appears in sequences

• Pseudoprimes to bases 2,5 and 7.at n=23A083736
• Numbers in A191311 but not in A129521.at n=33A191592
• Composite numbers k such that k divides Fibonacci(k+1) or Fibonacci(k-1) and 2^(k-1) == 1 (mod k).at n=16A214434
• 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=31A306310
• a(n) is the smallest n-gonal number that is a Fermat pseudoprime to base 2 (A001567), or -1 if no such number exists.at n=28A371759