|
| |
|
|
A136152
|
|
Composites one larger than a prime and with exactly three distinct prime factors.
|
|
5
|
|
|
|
30, 42, 60, 84, 90, 102, 110, 114, 132, 138, 140, 150, 168, 174, 180, 182, 198, 228, 230, 234, 240, 252, 258, 264, 270, 282, 294, 308, 312, 318, 348, 350, 354, 360, 374, 380, 402, 410, 434, 440, 444, 450, 468, 480, 492, 504, 522, 558, 564, 572, 588, 594, 600
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Harvey P. Dale, Table of n, a(n) for n = 1..1000
|
|
|
FORMULA
|
Find primes followed by N with exactly three prime factors, without repetition.
Equals A008864 INTERSECT A033992. - R. J. Mathar, Feb 20 2008
|
|
|
EXAMPLE
|
a(0)=30 because 30 follows the prime 29 and has three factors 2, 3 and 5.
|
|
|
MAPLE
|
isA008864 := proc(n) if n -prevprime(n) = 1 then true ; else false ; fi ; end: isA033992 := proc(n) if nops(numtheory[factorset](n)) = 3 then true ; else false ; fi ; end: isA136152 := proc(n) isA008864(n) and isA033992(n) ; end: for n from 1 do p := ithprime(n) ; if isA136152(p+1) then print(p+1) ; fi ; od: - R. J. Mathar, Feb 20 2008
|
|
|
MATHEMATICA
|
Select[Prime[Range[110]]+1, PrimeNu[#]==3&] (* From Harvey P. Dale, Apr 08 2012 *)
|
|
|
CROSSREFS
|
Cf. A136151 A136153 A136154 A136155.
Sequence in context: A091454 A175727 A179945 * A090815 A225228 A093599
Adjacent sequences: A136149 A136150 A136151 * A136153 A136154 A136155
|
|
|
KEYWORD
|
easy,nonn
|
|
|
AUTHOR
|
Enoch Haga, Dec 16 2007
|
|
|
EXTENSIONS
|
Edited by R. J. Mathar, Feb 20 2008
|
|
|
STATUS
|
approved
|
| |
|
|
