|
|
A344525
|
|
a(n) = Sum_{1 <= x_1, x_2, ... , x_n <= n} gcd(x_1,x_2, ... ,x_n).
|
|
6
|
|
|
1, 5, 30, 276, 3165, 47521, 826000, 16843792, 387723045, 10009889889, 285360865350, 8918311872516, 302888304741841, 11112685595264369, 437898699063881208, 18447025862624951488, 827242515246907227633, 39346558373191515582161
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
a(n) = Sum_{k=1..n} phi(k) * floor(n/k)^n.
|
|
MATHEMATICA
|
a[n_] := Sum[EulerPhi[k] * Quotient[n, k]^n, {k, 1, n}]; Array[a, 20] (* Amiram Eldar, May 22 2021 *)
|
|
PROG
|
(PARI) a(n) = sum(k=1, n, eulerphi(k)*(n\k)^n);
(Python)
from sympy import totient
def A344525(n): return sum(totient(k)*(n//k)**n for k in range(1, n+1)) # Chai Wah Wu, Aug 05 2024
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,changed
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|