|
|
A212718
|
|
Denominator of Sum_{k=1..n} 1/sigma(k).
|
|
4
|
|
|
1, 3, 12, 84, 28, 42, 168, 280, 3640, 32760, 32760, 32760, 4680, 1170, 4680, 145080, 145080, 145080, 145080, 1015560, 4062240, 4062240, 4062240, 4062240, 4062240, 4062240, 4062240, 4062240, 4062240, 4062240, 2031120, 2031120, 1015560, 3046680, 6093360, 6093360
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
1, 4/3, 19/12, 145/84, 53/28, 83/42, 353/168, …
|
|
MAPLE
|
with(numtheory): a:=n->numer(sum(1/sigma(k), k=1..n)): seq(a(n), n=1..50);
|
|
MATHEMATICA
|
Denominator[Table[Sum[1/DivisorSigma[1, k], {k, 1, n}], {n, 1, 50}]]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,frac
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|