Search: id:A101180
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%I A101180
%S A101180 0,8,671,15639,42159,981911,77624048,1807894920,4873553880,113507005568,
%T A101180 8973184757831,208989037004319,563373081435879
%N A101180 Numbers n such that 19*n^2 + 19*n + 1 is a square.
%C A101180 Define a(1)=0, a(2)=8, a(3)=671, a(4)=15639, a(5)=42159, a(6)=981911, 
               the first 6 terms found for the sequence then a(7)=57799*(2*a(3)+1)-a(2)-1, 
               a(8)=57799*(2*a(4)+1)-a(1)-1 for n>8 a(n)=57799*(2*a(n-4)+1)-a(n-8)-1 
               remark:57799 = 38*39*39+1 =2*19*(39^2)+1
%Y A101180 Cf. A105839.
%Y A101180 Sequence in context: A159621 A015106 A099126 this_sequence A128875 A037076 
               A116245
%Y A101180 Adjacent sequences: A101177 A101178 A101179 this_sequence A101181 A101182 
               A101183
%K A101180 nonn,more
%O A101180 1,2
%A A101180 Pierre CAMI (pierrecami(AT)tele2.fr), Apr 06 2005, Apr 22 2005
%E A101180 Edited by N. J. A. Sloane (njas(AT)research.att.com), Aug 29 2008 at 
               the suggestion of R. J. Mathar

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