%I A105842
%S A105842 0,55,9064,1480479,3140319,512899624,83770465015,13681996386240,
%T A105842 29021570410560
%N A105842 Numbers k such that 31*(k^2) + 31*k + 1 = n^2.
%F A105842 a(1)=0, a(2)=55, a(3)=9064, a(4)=1480479, a(5)=9241598*a(1)+4620798-a(4), 
               a(6)=9241598*a(2)+4620798-a(3), a(7)=9241598*a(3)+4620798-a(2), a(8)=9241598*a(4)+4620798-a(1), 
               then a(n)=9241598*a(n-4)+4620798-a(n-8)
%Y A105842 Cf. A105841.
%Y A105842 Sequence in context: A004708 A090813 A145617 this_sequence A113632 A163036 
               A033512
%Y A105842 Adjacent sequences: A105839 A105840 A105841 this_sequence A105843 A105844 
               A105845
%K A105842 nonn
%O A105842 1,2
%A A105842 Pierre CAMI (pierrecami(AT)tele2.fr), Apr 22 2005