1571328

Appears in sequences

• Reverse and add (in binary) - written in base 10.at n=31A035522
• Trajectory of 22 under the Reverse and Add! operation carried out in base 2.at n=30A061561
• Numbers m such that the sum of the first k divisors of m is equal to m for some k.at n=12A064510
• Numbers k such that there is a proper divisor d of k satisfying sigma(d)=k.at n=9A081756
• a(n) = 3*2^(n-1)*(2^n-1).at n=9A103897
• a(n) = 2*a(n-1) + 2*a(n-2) - 4*a(n-3) with n>2, a(0)=0, a(1)=1, a(2)=3.at n=20A135094
• Erdős-Nicolas numbers.at n=7A194472
• Trajectory of 26 under the Reverse and Add! operation carried out in base 2.at n=28A213012
• Numbers k for which sigma(k)/k - 1/4 is an integer.at n=6A218404
• Numbers n with the property that, if tau(n) = k = number of divisors of n, and the d(i) are the divisors [arranged in increasing order], then the sum 1/d(k) + 1/d(k-1) + 1/d(k-2) + ... + 1/d(q) is an integer for some q.at n=20A226476
• Numbers k such that k divides sigma(3*k).at n=22A227303
• Numbers k such that sigma(k) mod k = antisigma(k) mod k, where sigma(k) = A000203(k) = sum of divisors of k, antisigma(k) = A024816(k) = sum of non-divisors of k.at n=10A229088
• Numbers n such that denominator(sigma(sigma(n))/n) = denominator(sigma(sigma(s))/s) where s = sigma(n).at n=28A275321
• Numbers n that equal the sum of their first k consecutive aliquot bi-unitary divisors, but not all of them (i.e k < A286324(n)-1).at n=11A293618
• Sum of divisors of the multiply-perfect numbers.at n=9A307741
• Numbers m having at least one divisor d such that m divides sigma(d).at n=20A323652
• Bi-unitary arithmetic numbers k whose mean bi-unitary divisor is a bi-unitary divisor of k.at n=36A361787
• Numbers k such that sigma(k)/k - 1 equals (sigma(m)/m - 1)^2 for some m <= k.at n=9A381321
• Integers k such that sigma(k)/k - 1 is a rational square.at n=15A383482
• Integers x such that sigma(x)^2 - 3*x^2 is a square.at n=24A385810