OFFSET
1,2
FORMULA
a(n) = Sum_{k=1..n} k * (u(k) + v(n/k) - u(k)*v(n/k)), where u(n) is the prime characteristic (A010051) and v(n) = 1 - ceiling(n) + floor(n).
a(n) = sigma(n) - sopf(n) + Sum_{p<=n, p prime} p. - Wesley Ivan Hurt, Dec 31 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Feb 20 2022
STATUS
approved