272251

Appears in sequences

• Pseudoprimes (base-2) equal to product of 4 primes not necessarily distinct.at n=20A112441
• Pseudoprimes to base 2 of the form 4k+3.at n=15A177884
• Pseudoprimes divisible by a smaller pseudoprime.at n=18A215150
• Composite squarefree numbers k such that k^2-1 is divisible by p-1 and p+1, where p are all the prime factors of k.at n=10A306685
• 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=30A371759
• Expansion of 1/sqrt((1 - x^4 - x^5)^2 - 4*x^9).at n=52A376722