155272637520
domain: N
Appears in sequences
- a(n) = (1/C(2n,0) - 1/C(2n,1) + ... + d/C(2n,2n))*L, where d = (-1)^2n, L = LCM{C(2n,0), C(2n,1),..., C(2n,2n)}.at n=14A025535
- Least number m such that integer part of sigma(m)/phi(m) equals n.at n=33A070033
- Denominator of n*sum(k=1,(-1)^(k+1)/(n+k)).at n=14A082690
- Denominators of third-order harmonic numbers (defined by Conway and Guy, 1996).at n=28A124838
- Least number having the highest abundancy among numbers with exactly n prime factors (counted with multiplicity).at n=13A137825
- Denominator of Sum_{k=1..n} k*H_{n+k} where H_m = Sum_{i=1..m} 1/i.at n=30A144655
- m such that the integer part of sigma(m)/phi(m) is not attained by any integer less than m.at n=33A216920
- a(0)=1 and a(n)=prime(n)*lcm(prime(n)-1, a(n-1)) for n > 0.at n=10A226959
- a(n) = the smallest number k such that sigma(k) / phi(k) >= n.at n=33A291185