%I A089001
%S A089001 1,3,6,9,21,24,27,30,33,36,42,45,66,72,75,87,93,96,99,102,105,123,132,
%T A089001 135,153,156,162,177,186,189,201,204,219,228,237,240,255,264,273,285,
%U A089001 297,300,306,321,324,327,351,357,360,366,375,387,393,399,405,417,423
%N A089001 Numbers n such that 2*n^2 + 1 is prime.
%C A089001 All terms except the first one are multiples of 3. - Zak Seidov (zakseidov(AT)yahoo.com)
%F A089001 a(n)=((A090698(n)-1)/2)^(1/2).
%F A089001 Starting with n=2, a(n)=3*A089008(n-1). - Zak Seidov (zakseidov(AT)yahoo.com)
%Y A089001 Cf. A089008, A090612, A090698.
%Y A089001 Sequence in context: A018186 A015938 A116614 this_sequence A050889 A026095 
               A061929
%Y A089001 Adjacent sequences: A088998 A088999 A089000 this_sequence A089002 A089003 
               A089004
%K A089001 nonn
%O A089001 1,2
%A A089001 N. J. A. Sloane (njas(AT)research.att.com), Dec 20 2003