1004653

Appears in sequences

• a(n) is the smallest n-digit strong pseudoprime (in base 2).at n=3A062568
• a(n) is the smallest n-digit pseudoprime (to base 2).at n=4A068216
• Least triangular number whose digit permutations yield exactly n further triangular numbers.at n=13A095870
• Strong pseudoprimes (base-2) equal to product of 3 primes not necessarily distinct.at n=8A112450
• Intersection of A001567 and A212502.at n=25A212601
• Strong pseudoprimes (base 2) that become prime when two is subtracted.at n=9A230483
• Strong pseudoprimes k to base 2 such that either k-2 or k+2 is prime.at n=12A230487
• Composite numbers k congruent to 5 (mod 8) such that 2^((k-1)/2) mod k = k-1.at n=13A244626
• Fermat pseudoprimes to base 2 that are triangular.at n=23A293622
• The "non-residue" pseudoprimes: odd composite numbers n such that b(n)^((n-1)/2) == -1 (mod n), where base b(n) = A020649(n).at n=21A307767
• Fermat pseudoprimes to base 2 that are hexagonal.at n=22A322130
• Terms of A324315 (squarefree integers m > 1 such that if prime p divides m, then the sum of the base p digits of m is at least p) that are also hexagonal numbers (A000384) with index equal to their largest prime factor.at n=32A324319
• Odd composite numbers k such that 2^((k-1)/2) == -1 (mod k).at n=15A356638