OFFSET
1,4
EXAMPLE
a(4) = 2 because 4 has divisors 1, 2, and 4, and 4 - 1 = 3 and 4 - 2 = 2 are not squares.
MATHEMATICA
a[n_] := DivisorSum[n, 1 &, ! IntegerQ[Sqrt[n - #]] &]; Array[a, 100] (* Amiram Eldar, Feb 12 2023 *)
PROG
(Magma) [#[d: d in Divisors(n) | not IsSquare(n-d)]: n in [1..100]];
(PARI) a(n) = sumdiv(n, d, !issquare(n-d)); \\ Michel Marcus, Feb 12 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Feb 12 2023
STATUS
approved