|
| |
|
|
A088722
|
|
Number of divisors d>1 of n such that also d+1 divides n.
|
|
5
| |
|
|
0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 3, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 2, 0, 0, 0, 1, 0, 1, 0, 0, 0
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,12
|
|
|
COMMENTS
| a(A088723(n))>0, a(A088724(n))=1, a(A088725(n))=0;
a(A088726(n))=n, a(k)<>n, for n < A088726(n).
a(2n+1) = 0. - Chandler
|
|
|
EXAMPLE
| n=144: divisors(144)={1,2,3,4,6,8,9,12,16,18,24,36,48,72,144}, there are a(144)=3 divisors d>1 such that also d+1 divides 144: (2,3), (3,4) and (8,9).
|
|
|
CROSSREFS
| Cf. A088723, A088724, A088725, A088726.
Sequence in context: A082786 A101638 A070141 * A122180 A033772 A086015
Adjacent sequences: A088719 A088720 A088721 * A088723 A088724 A088725
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 12 2003
|
|
|
EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), May 29 2008
|
| |
|
|
