1379454720

Appears in sequences

• Multiply-perfect numbers: n divides sigma(n).at n=16A007691
• 4-perfect (quadruply-perfect or sous-triple) numbers: sum of divisors of n is 4n.at n=6A027687
• Multiply perfect numbers that are also harmonic numbers but are not arithmetic numbers.at n=7A046986
• Numbers k whose average divisor is nonintegral and divides k.at n=12A046999
• Numbers m such that m = sigma(abs(k)) - 3k, where k = sigma(m) - 3m.at n=12A069146
• Numbers k such that sigma(k)/k, sigma_3(k)/k and sigma_5(k)/k are all integers.at n=9A076231
• Numbers k such that sigma(k)/k and sigma_3(k)/k are both integers.at n=12A076233
• Numbers k such that sigma(k)/k, sigma_3(k)/k, sigma_5(k)/k and sigma_7(k)/k are all integers.at n=8A076234
• Numbers k such that there is a proper divisor d of k satisfying sigma(d)=k.at n=15A081756
• OU-Sigma multiperfect numbers.at n=21A091321
• Multiperfect numbers n which are divisible by sopfr(n) (multiperfect number: sigma(n) = k*n with k integer, sopfr: Sum of prime factors with repetition).at n=0A091443
• Numbers k such that S(S(k))=k, with S(n)=sigma(n)/4: 1/4-sociable numbers of order 1 or 2.at n=14A113286
• Let S(n)=sigma(|n|)-3*n; sequence gives numbers n such that S(S(S(S(n))))=n. May be called {3,1}-Sociable number of orders 1 or 2 or 4.at n=27A114528
• Multiperfect numbers sigma(n) = k*n, which are divisible by the sum of their prime factors without repetition.at n=4A114887
• Multiperfect numbers, sigma(n) = k*n, which are divisible by their sums of prime factors with and without repetition.at n=0A114888
• Multiply perfect numbers k such that sigma(k)/k > 2.at n=10A166069
• Numbers n such that gcd(sigma(n), n) > gcd(sigma(m), m) for all m < n.at n=29A216793
• Numbers k that divide 2*sigma(k).at n=26A246454
• Nonprime numbers k such that k | (sigma(k) - Sum_{j=1..m}{sigma(k) mod d_j}), where d_j is one of the m divisors of k.at n=21A282775
• Sum of divisors of the multiply-perfect numbers.at n=15A307741