OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Dedekind Function.
Wikipedia, Dedekind psi function.
FORMULA
a(p) = p + 2, p prime.
From Amiram Eldar, May 03 2023: (Start)
Multiplicative with a(p^e) = 1 + (p+1)*p^(e-1).
Sum_{k=1..n} a(k) ~ c * n^2, where c = (1/2) * Product_{p prime} (1/p^2 + 1/p + p/(1 + p)) = 1.00068765086778318519... . (End)
MATHEMATICA
f[p_, e_] := 1 + (p + 1)*p^(e - 1); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, May 03 2023 *)
CROSSREFS
KEYWORD
nonn,easy,mult
AUTHOR
Wesley Ivan Hurt, Apr 28 2023
STATUS
approved