OFFSET
1,3
FORMULA
a(n) = A061398(n) + 1.
EXAMPLE
MATHEMATICA
Table[Length[Select[Range[Prime[n], Prime[n+1]-1], SquareFreeQ]], {n, 100}]
PROG
(Python)
from math import isqrt
from sympy import prime, nextprime, mobius
def A373198(n):
p = prime(n)
q = nextprime(p)
r = isqrt(p-1)+1
return sum(mobius(k)*((q-1)//k**2) for k in range(r, isqrt(q-1)+1))+sum(mobius(k)*((q-1)//k**2-(p-1)//k**2) for k in range(1, r)) # Chai Wah Wu, Jun 01 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 29 2024
STATUS
approved