|
Search: id:A158337
|
|
|
| A158337 |
|
Composite numbers k such that k - number of prime factors of k = prime. |
|
+0
1
|
|
| 4, 8, 9, 15, 20, 21, 25, 33, 39, 44, 48, 49, 50, 55, 69, 70, 72, 76, 85, 91, 92, 108, 110, 111, 112, 115, 116, 129, 130, 131, 133, 135, 141, 154, 159, 162, 168, 169, 170, 182, 183, 201, 213, 230, 235, 236, 242, 244, 253, 259, 265, 266, 284, 286, 288, 295, 297, 309, 310, 312, 315, 316, 319, 320, 339
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
EXAMPLE
|
If composite=4=2*2 and 4-2=2=prime, then 4=a(1). If composite=8=2*2*2 and 8-3=5=prime, then 8=a(2). If compsite =9=3*3=and 9-2=7=prime, then 9=a(3), etc.
|
|
CROSSREFS
|
Cf. A000040, A002808.
|
|
KEYWORD
|
nonn,new
|
|
AUTHOR
|
Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Mar 16 2009, Nov 14 2009
|
|
|
Search completed in 0.002 seconds
|
