18705

Appears in sequences

• Fermat pseudoprimes to base 2, also called Sarrus numbers or Poulet numbers.at n=33A001567
• Divisors of 2^28 - 1.at n=34A003536
• Euler pseudoprimes: composite numbers n such that 2^((n-1)/2) == +-1 (mod n).at n=20A006970
• Composite numbers k such that k == +-1 (mod 8) and 2^((k-1)/2) == 1 (mod k).at n=15A006971
• a(n) = (n+1)*(2*n+1)*(3*n+1).at n=14A011199
• Pseudoprimes to base 11.at n=37A020139
• Self-convolution of composite numbers.at n=32A023648
• Euler-Jacobi pseudoprimes: 2^((n-1)/2) == (2 / n) mod n, where (2 / n) is a Jacobi symbol.at n=16A047713
• Sarrus numbers with more than 2 distinct prime factors.at n=18A080747
• Numbers with exactly one arithmetic progression of four successive divisors (not necessarily consecutive).at n=17A094530
• Pseudoquadprimes: p+4 for primes p where p+4 divides p^(p+4) + 4 and p+4 is composite.at n=10A100875
• Pseudoprimes (base-2) equal to product of 4 primes not necessarily distinct.at n=1A112441
• Nonprime integers n such that n divides A120492(n).at n=36A120329
• Limit of reversed rows of triangle A126347, in which row sums equal Bell numbers (A000110).at n=23A126348
• Sarrus numbers A001567 that are not Carmichael numbers A002997.at n=24A153508
• Increasing gaps between 2-pseudoprimes (upper end).at n=7A175737
• Pseudoprimes to base 2 of the form 4k+1.at n=27A178723
• Fermat pseudoprimes to base 2 of the form (6*k - 1)*((6*k - 2)*n + 1), where k and n are positive integers.at n=20A210993
• Pseudoprimes divisible by a smaller pseudoprime.at n=1A215150
• Fermat pseudoprimes to base 2 divisible by 5.at n=7A216023