130304

Appears in sequences

• Define the sequence T(a(0),a(1)) by a(n+2) is the greatest integer such that a(n+2)/a(n+1) < a(n+1)/a(n) for n >= 0. This is T(2,32).at n=4A022028
• Numbers k such that sigma(k) == 2 (mod k).at n=6A045768
• Numbers n such that sigma(n) = 2n + omega(n), where omega(n) is the number of distinct prime divisors of n.at n=6A063785
• The floor(1.001*x)-perfect numbers, where f-perfect numbers for an arithmetical function f are defined in A066218.at n=4A066239
• The floor(n/2)-perfect numbers, where f-perfect numbers for an arithmetical function f are defined in A066218.at n=8A066240
• The sum of the non-divisors of n (less than n) is a multiple of the sum of the divisors of n.at n=28A066860
• Numbers k such that sum of the divisors d of k divides 1 + 2 + ... + k = k(k+1)/2.at n=30A076617
• Numbers k whose abundance-radius does not exceed log(log(k)), i.e., abs(sigma(k)-2*k) <= log(log(k)).at n=19A088818
• Numbers k whose abundance is 2: sigma(k) - 2k = 2.at n=5A088831
• Admirable numbers whose abundance is < 10.at n=23A109788
• Admirable numbers such that the subtracted divisor is square.at n=23A109806
• Numbers n such that n and its 10's complement are both admirable numbers, i.e., n and 10^k - n where k is the number of digits in n are admirable.at n=8A110019
• Decimal number generated by the binary bits of the n-th generation of the Rule 110 elementary cellular automaton.at n=8A117999
• Abundant numbers n such that n/(sigma(n)-2n) is an integer.at n=37A153501
• 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=35A181595
• 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=19A181701
• Numbers of the form 2^(t-1)*(2^t-3), where 2^t-3 is prime.at n=4A181703
• Numbers m such that floor(antisigma(m) / m) = antisigma(m) mod m.at n=12A244324
• Numbers n whose sum of divisors equals the sum of divisors of 2n+1.at n=30A272553
• Admirable numbers such that the subtracted divisor is a Fibonacci number.at n=25A282754