|
| |
|
|
A274774
|
|
Least k such that sigma(k*n)/tau(k*n) = sigma(k*n+1)/tau(k*n+1), or 0 if no such k exists.
|
|
0
|
|
|
|
5, 7, 895, 1363, 1, 3353, 2, 2589, 1007, 10341, 1265, 1726, 7, 1, 179, 6634, 10052, 5745, 86, 53389, 958, 12165, 58, 863, 649, 250017, 2395, 6103, 46, 3447, 2714, 3317, 8110, 5026, 22653, 2812637, 94, 43, 16795, 58069, 61693, 479, 38, 52790, 1437, 29, 74, 2027510, 122367, 70545
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
Corresponding averages are 3, 6, 540, 840, 3, 2880, 6, 3240, 1170, 8640, 1596, 3240, 28, 6, 540, 9072, 15120, 8640, 330, 55440, 2880, 21924, 270, 3240, 1860, 875070, 7200, ...
|
|
|
LINKS
|
|
|
|
EXAMPLE
|
a(13) = 7 because sigma(7*13)/tau(7*13) = sigma(7*13+1)/tau(7*13+1).
|
|
|
MATHEMATICA
|
a[n_] := Block[{k=1}, While[! Equal @@ (DivisorSigma[1, n*k + {0, 1}] / DivisorSigma[ 0, n*k + {0, 1}]), k++]; k]; Array[a, 20] (* Giovanni Resta, Jul 28 2016 *)
|
|
|
PROG
|
(PARI) a(n) = {my(k=1); while (sigma(k*n)/numdiv(k*n) != sigma(k*n+1)/numdiv(k*n+1), k++); k; }
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
