131056
domain: N
Appears in sequences
- 2^(n-1)*A000668(n).at n=4A061029
- Numbers n such that usigma(cototient(n)) is a prime.at n=15A063719
- a(n) = 2^(n+1) - n.at n=15A095768
- Divisors of perfect numbers (A000396), sorted.at n=38A096360
- Values of A102370 which are >= a new power of 2.at n=16A103529
- Numerators of coefficients in expansion of x^-2*(1-exp(-2*x))^2.at n=12A104042
- Let S(n)=Sigma(n)/2. Numbers n such that S(S(n))=n, 1/2-Sociable number of order 1 or 2.at n=23A113791
- Row sums of triangle A132044.at n=17A132045
- Divisors of 33550336, the 5th perfect number.at n=17A133025
- Triangle read by rows: row n lists divisors of n-th perfect number A000396(n).at n=51A133031
- Divisors of 16775168 (half the 5th perfect number).at n=16A138815
- Triangle read by rows: row n lists the proper divisors of n-th perfect number A000396(n).at n=47A139246
- Triangle read by rows: row n lists the divisors of n-th perfect number A000396(n) that are multiples of n-th Mersenne prime A000668(n).at n=21A139247
- a(1)=1, a(n) = a(n-1) + n^3 if n odd, a(n) = a(n-1) + n^1 if n is even.at n=30A140153
- a(n) = 16*(2^n - 1).at n=13A175164
- Largest members of fully k-sociable cycles of order r.at n=22A183023
- Conjectured list of fully multisociable numbers.at n=42A183029
- Non-unitary amicable numbers.at n=23A259037
- Larger of a non-unitary amicable pair.at n=11A259039
- Number of n X n 0..1 arrays with exactly n+n-2 having value 1 and no three 1's forming an isosceles right triangle.at n=6A272951