|
| |
|
|
A133564
|
|
a(1)=1. a(n+1) = sum{k=isolated divisors of n} a(k). An isolated divisor, k, of n is a positive divisor of n where neither (k-1) nor (k+1) divides n.
|
|
1
| |
|
|
1, 1, 0, 1, 1, 2, 2, 3, 4, 5, 6, 7, 9, 10, 12, 14, 18, 19, 25, 26, 31, 34, 40, 41, 53, 55, 64, 69, 82, 83, 100, 101, 119, 126, 144, 148, 180, 181, 206, 216, 250, 251, 292, 293, 334, 352, 392, 393, 460, 463, 522, 541, 606, 607, 696, 704, 784, 810, 892, 893, 1026, 1027, 1127
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,6
|
|
|
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 isolated divisors of 20 are 10 and 20. Therefore a(21) = a(10) + a(20) = 5 + 26 = 31.
|
|
|
CROSSREFS
| Cf. A133565.
Sequence in context: A011873 A173151 A008673 * A017863 A088567 A029014
Adjacent sequences: A133561 A133562 A133563 * A133565 A133566 A133567
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Leroy Quet Sep 16 2007
|
|
|
EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 25 2008
|
| |
|
|
