|
| |
|
|
A069288
|
|
Number of odd divisors of n <= sqrt(n).
|
|
7
|
|
|
|
1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 3, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 1, 2, 1, 1, 3, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 3, 1, 1, 3, 1, 2, 2, 1, 1, 2, 3, 1, 2, 1, 1, 3, 1, 2, 2, 1, 2, 3, 1, 1, 3, 2, 1, 2, 1, 1, 4
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,9
|
|
|
COMMENTS
|
a(n) = #{d : d = A182469(n,k), d <= A000196(n), k=1..A001227(n)}. - Reinhard Zumkeller, Apr 05 2015
|
|
|
LINKS
|
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
|
|
|
FORMULA
|
G.f.: sum(n>=1, 1/(1-q^(2*n-1)) * q^((2*n-1)^2) ) [Joerg Arndt, Mar 04 2010]
|
|
|
MATHEMATICA
|
odn[n_]:=Count[Divisors[n], _?(OddQ[#]&&#<=Sqrt[n ]&)]; Array[odn, 100] (* Harvey P. Dale, Nov 04 2017 *)
|
|
|
PROG
|
(PARI) a(n) = my(ir = sqrtint(n)); sumdiv(n, d, (d % 2) * (d <= ir)); \\ Michel Marcus, Jan 14 2014
(Haskell)
a069288 n = length $ takeWhile (<= a000196 n) $ a182469_row n
-- Reinhard Zumkeller, Apr 05 2015
|
|
|
CROSSREFS
|
Cf. A001227, A000005, A069289.
Cf. A000196, A182469, A001227.
Sequence in context: A115574 A115577 A115570 * A152831 A097795 A161076
Adjacent sequences: A069285 A069286 A069287 * A069289 A069290 A069291
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Reinhard Zumkeller, Mar 14 2002
|
|
|
STATUS
|
approved
|
| |
|
|
