OFFSET
1,1
COMMENTS
All terms > 17 are congruent to 1 mod 6. - Zak Seidov, Dec 03 2010
LINKS
T. D. Noe, Table of n, a(n) for n=1..1000
FORMULA
a(n) = 6*A342564(n-1) + 1 for n >= 2. - Hugo Pfoertner, Jun 24 2021
EXAMPLE
487*491+2=239119.
MAPLE
with (numtheory): for n from 1 to 1000 do if (tau(ithprime(n)*ithprime(n+1)+2)=2) then print(ithprime(n), ithprime(n+1), ithprime(n)*ithprime(n+1)+2); fi; od;
MATHEMATICA
Reap[Do[If[PrimeQ[p=Prime[k]*Prime[k+1]+2], Sow[p]], {k, 1, 430}]][[2, 1]] (* Zak Seidov Dec 03 2010 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Herman H. Rosenfeld (herm3(AT)pacbell.net)
EXTENSIONS
Corrected and extended by Joe DeMaio (jdemaio(AT)kennesaw.edu).
STATUS
approved