654848

Appears in sequences

• Numbers m such that 2*m - sigma(m) is a divisor of m and greater than one, where sigma = A000203 is the sum of divisors.at n=30A060326
• Numbers n such that phi(n) is the sum of the first k divisors of n for some k.at n=29A072278
• Number of (w,x,y,z) with all terms in {1,...,n} and w<=|x-y|+|y-z|.at n=32A212673
• Deficient-perfect numbers: Deficient numbers n such that n/(2n-sigma(n)) is an integer.at n=50A271816
• Number of graceful labelings of the n-cycle graph.at n=13A333720
• a(n) is the smallest multiple k of 2^n such that |sigma(k) - 2*k| = 2^n, where sigma = A000203.at n=8A363285
• E.g.f. A(x) satisfies A(x) = 1 + sinh(x*A(x)) / A(x).at n=10A381179