27846

Appears in sequences

• Harmonic or Ore numbers: numbers k such that the harmonic mean of the divisors of k is an integer.at n=14A001599
• Numbers whose divisors' harmonic and arithmetic means are both integers.at n=11A007340
• a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (1, p(1), p(2), ...).at n=32A024479
• Denominators of continued fraction convergents to sqrt(870).at n=5A042681
• (1+e)-harmonic numbers: harmonic mean of (1+e)-divisors is an integer.at n=14A053783
• Expansion of (3+10*x+3*x^2)/(1-x)^12.at n=5A059624
• Composite numbers k such that the difference between the odd and even aliquot parts of k divides k.at n=26A066193
• Numbers n such that harmonic mean of the divisors of n is a prime.at n=6A074247
• Numbers whose number of divisors equals the sum of their separate prime-power decompositions.at n=13A087004
• a(n) = (2^(3*n-1))/(integral_{x=0..1} (1-x^4)^n dx).at n=4A088505
• Duplicate of A007340.at n=11A090944
• Harmonic numbers (A001599) which are not perfect (A000396).at n=10A090945
• a(n) = smallest number m such that m*tau(m)/sigma(m) = n, or 0 if no such m exists.at n=16A091911
• Numbers k such that the digits of sigma(k) are a permutation of those of k, in base 10.at n=28A115920
• a(n) = 3*n^3 + 3*n.at n=21A119536
• Array of T(n,m)=1*5*...*(4n-3)*3*7*...*(4m-1)*2^(n+m)/(n+m)! by antidiagonals.at n=38A122882
• Composite numbers such that the square root of the sum of squares of their prime factors is a prime.at n=14A134607
• Harmonic numbers that are not multiply-perfect.at n=8A140798
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 1), (-1, 1, 0), (1, 0, -1), (1, 1, 0)}.at n=10A148605
• Minimal covering numbers.at n=21A160559