32128
domain: N
Appears in sequences
- a(n) is the concatenation of n and 4n.at n=31A019552
- Numbers k such that sigma(k) == 4 (mod k).at n=9A045769
- Numbers k such that sigma(k) == 0 (mod k+2).at n=7A067702
- Even and odd solutions to abs(sigma(x)-2x) <= log(x). Numbers n whose abundance-radius does not exceed log(n).at n=41A088011
- Numbers k whose abundance is 4: sigma(k) - 2*k = 4.at n=6A088832
- Admirable Harshad numbers such that the subtracted divisor is also a Harshad number.at n=24A109396
- Admirable numbers such that the subtracted divisor is prime.at n=8A109766
- Admirable numbers whose abundance is < 10.at n=17A109788
- Near-multiperfects with primes excluded, abs(sigma(m) mod m) <= log(m).at n=44A117347
- Near-multiperfects with primes and powers of 2 excluded, abs(sigma(m) mod m) <= log(m).at n=31A117348
- Near-multiperfects with primes, powers of 2 and 6 * prime excluded, abs(sigma(n) mod n) <= log(n).at n=31A117349
- Abundant numbers n such that n/(sigma(n)-2n) is an integer.at n=32A153501
- Abundant numbers n for which the abundance d = sigma(n) - 2*n is a proper divisor, that is, 0 < d < n and d | n.at n=30A181595
- (N\{4})-perfect numbers, i.e., numbers m for which sigma(m)-4 = 2m, if 4|m, otherwise sigma(m) = 2m.at n=4A181597
- Near-perfect numbers (A181595) of the form 2^(t-1)*(2^t-2^k-1), where 2^t-2^k-1 is prime, k>=1, t>k.at n=15A181701
- Numbers m=2^(t-1)*(2^t-5), where 2^t-5 is prime.at n=3A181704
- Number of ways to place 2 non-attacking wazirs on an n X n toroidal board.at n=15A201236
- Admirable numbers such that the subtracted divisor is a Fibonacci number.at n=22A282754
- Decimal representation of the diagonal from the origin to the corner of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 187", based on the 5-celled von Neumann neighborhood.at n=14A286502
- Decimal representation of the diagonal from the origin to the corner of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 305", based on the 5-celled von Neumann neighborhood.at n=14A287546