OFFSET
1,1
COMMENTS
Corresponding semiprimes k^2+1 are in A144255.
Solutions to the equation: A000005(1+k^2) = 4. - Enrique Pérez Herrero, May 03 2012
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
FORMULA
MATHEMATICA
lst={}; Do[If[Plus@@Last/@FactorInteger[n^2+1]==2, AppendTo[lst, n]], {n, 0, 200}]; lst (* Vladimir Joseph Stephan Orlovsky, Mar 24 2009 *)
Select[Range[200], PrimeOmega[#^2+1]==2&] (* Harvey P. Dale, Feb 28 2013 *)
PROG
(PARI) select(vector(50, n, n), n->bigomega(n^2+1)==2)
\\ Zak Seidov, Feb 25 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jason Earls, Jul 20 2003
STATUS
approved