A136152 Composites one larger than a prime and with exactly three distinct prime factors.

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

Offset: 1

Author

Enoch Haga, Dec 16 2007

Keywords

• easy
• nonn

Examples

			a(0)=30 because 30 follows the prime 29 and has three factors 2, 3 and 5.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A136151, A136153, A136154, A136155.

Programs

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&] (* Harvey P. Dale, Apr 08 2012 *)

Formula

Find primes followed by N with exactly three prime factors, without repetition.

Equals A008864 INTERSECT A033992. - R. J. Mathar, Feb 20 2008

Extensions

Edited by R. J. Mathar, Feb 20 2008