|
|
A344403
|
|
a(n) = Sum_{d|n} d * floor(n/d^2).
|
|
2
|
|
|
1, 2, 3, 6, 5, 8, 7, 12, 12, 14, 11, 21, 13, 20, 18, 28, 17, 32, 19, 34, 27, 32, 23, 46, 30, 38, 36, 46, 29, 58, 31, 56, 42, 50, 40, 80, 37, 56, 51, 73, 41, 80, 43, 74, 65, 68, 47, 105, 56, 84, 66, 90, 53, 104, 65, 103, 75, 86, 59, 136, 61, 92, 91, 120, 75, 125, 67, 118, 90
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
If p is prime, a(p) = Sum_{d|p} d * floor(p/d^2) = 1*p + p*0 = p.
|
|
LINKS
|
|
|
EXAMPLE
|
a(6) = 8; Sum_{d|6} d * floor(6/d^2) = 1*6 + 2*1 + 3*0 + 6*0 = 8.
|
|
MATHEMATICA
|
Table[Sum[(1 - Ceiling[n/k] + Floor[n/k]) k*Floor[n/k^2], {k, n}], {n, 100}]
|
|
PROG
|
(PARI) a(n) = sumdiv(n, d, d*(n\d^2)); \\ Michel Marcus, May 17 2021
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|