OFFSET
1,2
LINKS
FORMULA
a(1) = 0; for n > 1, if n is of the form p^k (p prime and exponent k >= 1), then a(n) = n, otherwise a(n) > n.
MATHEMATICA
Join[{0}, Table[DivisorSigma[1, n]-DivisorSigma[1, Divisors[n][[-2]]], {n, 2, 100}]] (* Harvey P. Dale, Jan 12 2022 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 06 2019
STATUS
approved