OFFSET
1,1
COMMENTS
It appears that there is only one known example of three consecutive primes p, q, r whose product is 1 more than a perfect cube, namely 7*11*13 = 1001 and that probably no other examples exist. - N. J. A. Sloane, Apr 27 2008
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
k^3+1=p*q*r where p, q, r are primes (not necessarily distinct).
EXAMPLE
9 is a member because 9^3+1=730=2*5*73 (product of three primes).
MATHEMATICA
Select[Range[370], PrimeOmega[#^3+1]==3&] (* James C. McMahon, Aug 10 2024 *)
PROG
(PARI) isok(n) = bigomega(n^3+1) == 3; \\ Michel Marcus, Oct 10 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Mar 08 2006
STATUS
approved