|
Search: id:A136155
|
|
|
| A136155 |
|
Composites one larger than a prime and with exactly two or three distinct prime factors. |
|
+0
5
|
|
| 6, 12, 14, 18, 20, 24, 30, 38, 42, 44, 48, 54, 60, 62, 68, 72, 74, 80, 84, 90, 98, 102, 104, 108, 110, 114, 132, 138, 140, 150, 152, 158, 164, 168, 174, 180, 182, 192, 194, 198, 200, 212, 224, 228, 230, 234, 240, 242, 252, 258, 264, 270, 272, 278, 282, 284, 294
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
FORMULA
|
Union of A136151 and A136152. Subset of A008864. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 24 2008
A136151 UNION A136152. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 03 2008
|
|
EXAMPLE
|
a(1)=6, which is one larger than the prime 5 and has 2 distinct prime factors (namely 2 and 3).
60 is in the sequence because 59 is prime and 60 = 2^2*3*5 has three distinct prime factors.
|
|
MAPLE
|
A001221 := proc(n) nops(numtheory[factorset](n)) ; end: isA136155 := proc(n) if isprime(n-1) then RETURN( A001221(n)=2 or A001221(n)= 3) ; else RETURN(false) ; fi ; end: for n from 1 to 300 do if isA136155(n) then printf("%d, ", n) ; fi ; od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 03 2008
|
|
CROSSREFS
|
Cf. A136151 A136152 A136153 A136154.
Sequence in context: A055051 A143957 A105115 this_sequence A136151 A056774 A031405
Adjacent sequences: A136152 A136153 A136154 this_sequence A136156 A136157 A136158
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Enoch Haga (Enokh(AT)comcast.net), Dec 16 2007
|
|
EXTENSIONS
|
Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl) and Jens Kruse Andersen (jens.k.a(AT)get2net.dk), Apr 24 2008
|
|
|
Search completed in 0.002 seconds
|
