OFFSET
1,1
COMMENTS
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..10545
FORMULA
EXAMPLE
a(2) = 21: 3^3 - 2*3 = 27 - 6 = 21 = 3 * 7, which is semiprime.
a(3) = 115: 5^3 - 2*5 = 125 - 10 = 115 = 5 * 23, which is semiprime.
MAPLE
select(k -> numtheory:-bigomega(k)=2, [seq((n^3-2*n), n=1..500)]);
MATHEMATICA
Select[Table[n^3 - 2*n, {n, 1000}], PrimeOmega[#] == 2 &]
PROG
(PARI) forprime(p=1, 10^3, q=p^2-2; if(isprime(q), print1(p*q, ", "))) \\ Derek Orr, Aug 17 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
K. D. Bajpai, Aug 17 2014
STATUS
approved