|
| |
|
|
A090552
|
|
a(1)=1; for n>1, a(n) is the smallest positive integer for which sigma(a(n)) is a multiple of sigma(a(n-1)).
|
|
1
| |
|
|
1, 2, 5, 6, 11, 14, 15, 23, 30, 46, 51, 55, 66, 70, 94, 115, 119, 138, 154, 165, 210, 282, 310, 322, 345, 357, 382, 385, 462, 658, 682, 705, 759, 766, 805, 930, 966, 1146, 1155, 1270, 1426, 1491, 1551, 1581, 1645, 1705, 1771, 1915, 1974, 2046, 2170, 2298, 2415
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
EXAMPLE
| After a(4)=6, with sigma(6)=12, the smallest number k such that sigma(k) is a multiple of 12 is 11, with sigma(11)=12. Thus a(5)=11.
|
|
|
CROSSREFS
| Cf. A090553.
Sequence in context: A045845 A002133 A092306 * A024520 A015613 A135013
Adjacent sequences: A090549 A090550 A090551 * A090553 A090554 A090555
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Dec 09 2003
|
|
|
EXTENSIONS
| Corrected, extended and edited by John W. Layman (layman(AT)math.vt.edu), Aug 10 2004
|
| |
|
|
