|
|
|
|
1, 3, 7, 8, 13, 19, 19, 20, 33, 35, 31, 48, 37, 51, 75, 48, 49, 87, 55, 88, 109, 83, 67, 116, 105, 99, 135, 128, 85, 195, 91, 112, 177, 131, 199, 216, 109, 147, 211, 212, 121, 283, 127, 208, 333, 179, 139, 272, 217, 275, 279, 248, 157, 351, 323, 308, 313, 227, 175
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
LINKS
|
|
|
FORMULA
|
a(n) = Sum_{k=0..4n+2} gcd(4n-k+3, k+1)/4.
|
|
MATHEMATICA
|
Table[Sum[GCD[4n-k+3, k+1]/4, {k, 0, 4n+2}], {n, 0, 60}] (* Harvey P. Dale, May 19 2019 *)
f[p_, e_] := (e*(p - 1)/p + 1)*p^e; a[n_] := (Times @@ f @@@ FactorInteger[4*n+4]) / 4 - n - 1; Array[a, 100, 0] (* Amiram Eldar, Apr 26 2023 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|