20145
domain: N
Appears in sequences
- Numbers k such that k and k+1 have same sum of divisors.at n=12A002961
- Numbers k such that k and k+1 have the same sum but an unequal number of divisors.at n=8A054007
- Numbers k such that sigma(k) divides sigma(k+1), where sigma(k) is sum of positive divisors of k.at n=24A058072
- Numbers k such that sigma(k+1) divides sigma(k), where sigma(k) is the sum of positive divisors of k.at n=29A058073
- Integer part of log(n!)^(1 + log(log(1 + n))).at n=31A062475
- Nearest integer to log(n!)^(1 + log(log(1 + n))).at n=31A062476
- Numbers k such that k and k+1 have the same sum of squarefree divisors, or sqf(k) = sqf(k+1), where sqf(k) = A048250(k).at n=10A063964
- Numbers k such that k and k+1 have the same sum of unitary divisors (A034448).at n=31A064125
- Numbers k such that k and k+1 have the same sum of unitary and nonunitary divisors.at n=5A064729
- Numbers k such that gcd(sigma(k), sigma(k+1)) > k.at n=40A066025
- Look at the first 10 digits of the sequence: they are all different. The same for the next 10. And the next 10, etc. This sequence is the slowest increasing one with that property.at n=50A097912
- Lexicographically earliest sequence of positive integers with the property that a(a(n)) = a(1)+a(2)+...+a(n).at n=26A105753
- G.f. is the polynomial (1-x^3) * (1-x^6) * (1-x^9) * (1-x^12) * (1-x^15) * (1-x^18) / (1-x)^6.at n=23A162539
- G.f. is the polynomial (1-x^3) * (1-x^6) * (1-x^9) * (1-x^12) * (1-x^15) * (1-x^18) / (1-x)^6.at n=34A162539
- Numbers k such that sigmawt(k) = sigmawt(k+1), where sigmawt(k) is the sum of the divisors of k weighted by divisor multiplicity in k.at n=6A171183
- Number of permutations of n objects such that no three-element subset is preserved.at n=8A213322
- Number of permutations of n objects such that no five-element subset is preserved.at n=8A213324
- Numbers n such that sigma(n+1) - sigma(n) = k*n for some integer k, where sigma(n) = A000203 (sum of divisors of n).at n=20A223136
- Table of consecutive numbers with the same sum of divisors.at n=24A225757
- Smallest m such that gcd(A227113(m+1), A227113(m)) = n.at n=38A227289