A347157 Sum of cubes of distinct prime divisors of n that are < sqrt(n).

0, 0, 0, 0, 0, 8, 0, 8, 0, 8, 0, 35, 0, 8, 27, 8, 0, 35, 0, 8, 27, 8, 0, 35, 0, 8, 27, 8, 0, 160, 0, 8, 27, 8, 125, 35, 0, 8, 27, 133, 0, 35, 0, 8, 152, 8, 0, 35, 0, 133, 27, 8, 0, 35, 125, 351, 27, 8, 0, 160, 0, 8, 370, 8, 125, 35, 0, 8, 27, 476, 0, 35, 0, 8, 152

Offset

1,6

Links

Table of n, a(n) for n=1..75.

Formula

G.f.: Sum_{k>=1} prime(k)^3 * x^(prime(k)*(prime(k) + 1)) / (1 - x^prime(k)).

Mathematica

Table[DivisorSum[n, #^3 &, # < Sqrt[n] && PrimeQ[#] &], {n, 1, 75}]
nmax = 75; CoefficientList[Series[Sum[Prime[k]^3 x^(Prime[k] (Prime[k] + 1))/(1 - x^Prime[k]), {k, 1, nmax}], {x, 0, nmax}], x] // Rest

Crossrefs

Cf. A001158, A005064, A005067, A333806, A333808, A339354, A347156, A347158.

Sequence in context: A048729 A003131 A010679 * A186981 A347159 A156744

Adjacent sequences: A347154 A347155 A347156 * A347158 A347159 A347160

Keyword

nonn

Author

Ilya Gutkovskiy, Aug 20 2021

Status

approved