269011

Appears in sequences

• Strong pseudoprimes to base 31.at n=31A020257
• Strong pseudoprimes to base 61.at n=36A020287
• Strong pseudoprimes to base 66.at n=34A020292
• Strong pseudoprimes to base 88.at n=32A020314
• Lexicographically earliest sequence of pairwise coprime triangular numbers.at n=32A034792
• Triangular numbers which are the product of two primes.at n=38A068443
• Odd composites with increasing proportion of nontrivial non-witnesses of compositeness by the Miller-Rabin primality test.at n=11A090659
• Records in A111273.at n=21A113732
• Triangular numbers that are also brilliant (A078972).at n=31A113940
• Numbers of the form p*q, p and q prime with q=2*p-1.at n=17A129521
• Odd numbers with increasing numbers of bases to which they are strong pseudoprimes.at n=23A141768
• a(n) = m*(m+1)/2, where m = floor(n^(5/2)).at n=13A185542
• 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=35A191311
• Odd non-Carmichael numbers with increasing numbers of bases to which they are pseudoprimes.at n=33A194946
• Fermat pseudoprimes n to base 3 for which sqrt(8*n + 1) is an integer.at n=23A217841
• Squarefree numbers (from A005117) with prime divisors in a 2p-1 progression.at n=19A231814
• Record values in A265388.at n=20A265395
• a(n) is the smallest k such that the p-rank of (Z/kZ)* is 2, where p = prime(n) and (Z/kZ)* is the multiplicative group of integers modulo n.at n=17A307434
• Odd numbers > 1, not powers of primes, for which A326147(n) is equal to abs(A326146(n)).at n=24A326148
• Odd composite numbers k for which the number of witnesses for strong pseudoprimality of k equals phi(k)/4, where phi is the Euler totient function (A000010).at n=12A329759