226801

Appears in sequences

• Strong pseudoprimes to base 3.at n=33A020229
• Strong pseudoprimes to base 14.at n=34A020240
• Lexicographically earliest sequence of pairwise coprime triangular numbers.at n=30A034792
• Triangular numbers which are the product of two primes.at n=36A068443
• Smallest triangular number k such that k-1 has exactly n (not necessarily distinct) prime factors.at n=10A081950
• Pseudoprimes to bases 2 and 7.at n=15A083733
• Pseudoprimes to bases 3 and 7.at n=19A083735
• Pseudoprimes to bases 2,3 and 7.at n=10A083738
• Brilliant Sarrus numbers.at n=19A086837
• Records in A111273.at n=20A113732
• Triangular numbers that are also brilliant (A078972).at n=29A113940
• Semiprimes in A006987(n), or semiprime binomial coefficients: C(n,k), 2 <= k <= n-2.at n=37A124000
• Numbers of the form p*q, p and q prime with q=2*p-1.at n=16A129521
• Overpseudoprimes to base 3.at n=17A141350
• Composite numbers k such that 2^k-2 and 3^k-3 are both divisible by k and k is not a Carmichael number (A002997).at n=13A153513
• Numbers m such that exactly half of the a such that 0<a<m and (a,m)=1 satisfy a^(m-1) == 1 (mod m).at n=32A191311
• Odd non-Carmichael numbers with increasing numbers of bases to which they are pseudoprimes.at n=32A194946
• Poulet numbers (2-pseudoprimes) of the form 7200*n^2 + 8820*n + 2701.at n=4A214016
• Fermat pseudoprimes n to base 3 for which sqrt(8*n + 1) is an integer.at n=22A217841
• Squarefree numbers (from A005117) with prime divisors in a 2p-1 progression.at n=18A231814