|
|
A193349
|
|
Sum of odd divisors of tau(n).
|
|
1
|
|
|
1, 1, 1, 4, 1, 1, 1, 1, 4, 1, 1, 4, 1, 1, 1, 6, 1, 4, 1, 4, 1, 1, 1, 1, 4, 1, 1, 4, 1, 1, 1, 4, 1, 1, 1, 13, 1, 1, 1, 1, 1, 1, 1, 4, 4, 1, 1, 6, 4, 4, 1, 4, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 4, 8, 1, 1, 1, 4, 1, 1, 1, 4, 1, 1, 4, 4, 1, 1, 1, 6, 6, 1, 1, 4, 1, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,4
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 1 if and only if n is in A036537.
a(n) = A062069(n) if and only if n is a square. (End)
|
|
EXAMPLE
|
a(36) = 13 because tau(36) = 9 and the sum of the 3 odd divisors {1, 3, 9} is 13.
|
|
MATHEMATICA
|
Table[Total[Select[Divisors[DivisorSigma[0, n]], OddQ[ # ]&]], {n, 80}]
|
|
PROG
|
(PARI) a(n)=sumdiv(sigma(n, 0), d, (d%2)*d);
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,changed
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|