|
| |
|
|
A133780
|
|
Irregular array: n-th row lists the "non-isolated divisors" of (2n). A positive divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n.
|
|
2
| |
|
|
1, 2, 1, 2, 1, 2, 3, 1, 2, 1, 2, 1, 2, 3, 4, 1, 2, 1, 2, 1, 2, 3, 1, 2, 4, 5, 1, 2, 1, 2, 3, 4, 1, 2, 1, 2, 1, 2, 3, 5, 6, 1, 2, 1, 2, 1, 2, 3, 4, 1, 2, 1, 2, 4, 5, 1, 2, 3, 6, 7, 1, 2, 1, 2, 1, 2, 3, 4, 1, 2, 1, 2, 1, 2, 3, 1, 2, 7, 8, 1, 2, 1, 2, 3, 4, 5, 6, 1, 2, 1, 2, 1, 2, 3, 1, 2, 1, 2, 1, 2, 3, 4, 8, 9, 1
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| No odd integer has any non-isolated divisors. The number of terms in the n-th row of the array is A132747(2n).
|
|
|
EXAMPLE
| The positive divisors of 20 are 1,2,4,5,10,20. Of these, 1 and 2 are adjacent and 4 and 5 are adjacent. So the non-isolated divisors of 20 are 1,2,4,5.
|
|
|
CROSSREFS
| Cf. A133779, A132747, A132748.
Sequence in context: A102566 A134156 A067815 * A080237 A136109 A105265
Adjacent sequences: A133777 A133778 A133779 * A133781 A133782 A133783
|
|
|
KEYWORD
| nonn,tabf
|
|
|
AUTHOR
| Leroy Quet, Sep 23 2007
|
|
|
EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 24 2008
|
| |
|
|
