OFFSET
1,1
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..10000
EXAMPLE
247 is in the sequence because 7^2 + 7*11 + 11^2 = 247 = 13*19, which is semiprime.
679 is in the sequence because 13^2 + 13*17 + 17^2 = 679 = 7*97, which is semiprime.
MAPLE
MATHEMATICA
Select[Table[Prime[n]^2 + Prime[n] Prime[n + 1] + Prime[n + 1]^2, {n, 100}], PrimeOmega[#] == 2 &]
PROG
(PARI) issemi(n)=bigomega(n)==2
list(lim)=my(v=List(), p=3, t); forprime(q=5, , t=p^2+p*q+q^2; if(t>lim, break); if(issemi(t), listput(v, t)); p=q); Vec(v) \\ Charles R Greathouse IV, Jul 05 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Jun 14 2014
STATUS
approved