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

1,1

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

Crossrefs

Cf. A136151, A136153, A136154, A136155.

Sequence in context: A296717 A302753 A179945 * A244066 A090815 A238367

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