|
|
A342396
|
|
a(n) = Sum_{k=1..n} k^(n/gcd(k,n) - 1).
|
|
2
|
|
|
1, 2, 6, 31, 355, 3150, 67172, 904085, 22998481, 427799450, 14914341926, 287337926355, 13421957361111, 339940911160914, 15434209582905140, 493467700905592777, 28101527071305611529, 836396358233559195382
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
If p is prime, a(p) = A031971(p-1) + 1.
|
|
MATHEMATICA
|
a[n_] := Sum[k^(n/GCD[k, n] - 1), {k, 1, n}]; Array[a, 18] (* Amiram Eldar, Mar 10 2021 *)
|
|
PROG
|
(PARI) a(n) = sum(k=1, n, k^(n/gcd(k, n)-1));
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|