643336

Appears in sequences

• Smaller members of regular amicable pairs.at n=25A215491
• Numbers n such that sigma(n) = sigma(n - phi(n)), where sigma(n) is the sum of divisors of n and phi(n) is the Euler totient function of n.at n=13A228519
• Untouchable amicable numbers: amicable pairs which cannot be reached by any aliquot sequence starting from a number that does not belong to this pair.at n=2A238382
• Smaller of amicable pair (x, y) as they are listed in A259933.at n=32A260086
• Twin amicable numbers (m,n) where there is not any part of another amicable pair between m and n.at n=30A273259
• Amicable pairs where only deficient aliquot parts are considered.at n=10A280516
• Lesser of tri-unitary amicable numbers pair: numbers (m, n) such that tsigma(m) = tsigma(n) = m + n, where tsigma(n) is the sum of the tri-unitary divisors of n (A324706).at n=32A324708
• Amicable pairs with the property that the number of divisors of the smaller member is twice the number of divisors of the larger member.at n=32A328065
• Primitive abundant numbers (A071395) with a record gap to the next primitive abundant number.at n=13A334419
• Lesser of a pair of S-amicable numbers k < m such that s(k) = m and s(m) = k, where s(k) = A364858(k).at n=7A364859