81631

Appears in sequences

• Strong pseudoprimes to base 42.at n=25A020268
• Positions of A080313 in A014486.at n=38A080312
• Numbers k for which phi(A267099(k)) is equal to phi(k), but the number of 4m+1 and 4m+3 primes in the prime factorization of k (when counted with multiplicity) is not equal. Here A267099 is fully multiplicative involution swapping the positions of 4m+1 and 4m+3 primes, and phi is Euler totient function.at n=4A354194
• Heptagonal numbers which are products of three distinct primes.at n=36A356422