OFFSET
1,4
COMMENTS
Number of terms of A235992 that divide n. - Antti Karttunen, May 13 2024
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
FORMULA
EXAMPLE
a(12) = 3; 12 has 3 divisors whose arithmetic derivatives are even: 1' = 0, 4' = 4, and 12' = 16.
MATHEMATICA
d[1] = 0; d[n_] := n*Plus @@ ((Last[#]/First[#]) & /@ FactorInteger[n]); a[n_] := DivisorSum[n, 1 &, EvenQ[d[#]] &]; Array[a, 100] (* Amiram Eldar, May 02 2022 *)
PROG
(PARI) ad(n) = vecsum([n/f[1]*f[2]|f<-factor(n+!n)~]); \\ A003415
a(n) = sumdiv(n, d, !(ad(d) % 2)); \\ Michel Marcus, May 02 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, May 01 2022
EXTENSIONS
Data section extended up to a(105) by Antti Karttunen, May 13 2024
STATUS
approved