OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
From Amiram Eldar, Nov 21 2022: (Start)
MATHEMATICA
DivisorSigma[1, #]&/@Select[Range[150], SquareFreeQ] (* Harvey P. Dale, May 18 2014 *)
PROG
(PARI) j=[]; for(n=1, 200, if(issquarefree(n), j=concat(j, sigma(n)))); j
(Haskell)
a062822 1 = 1
a062822 n = product $ map (+ 1) $ a265668_row n
-- Reinhard Zumkeller, Dec 13 2015
(Python)
from math import isqrt
from sympy import mobius, divisor_sigma
def A062822(n):
def f(x): return n+x-sum(mobius(k)*(x//k**2) for k in range(1, isqrt(x)+1))
m, k = n, f(n)
while m != k:
m, k = k, f(k)
return divisor_sigma(m) # Chai Wah Wu, Aug 12 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 20 2001
STATUS
approved