%I A084158
%S A084158 0,1,5,30,174,1015,5915,34476,200940,1171165,6826049,39785130,231884730,
%T A084158 1351523251,7877254775,45912005400,267594777624,1559656660345,
%U A084158 9090345184445,52982414446326,308804141493510,1799842434514735
%N A084158 a(n)=A000129(n)*A000129(n+1)/2
%C A084158 May be called Pell triangles.
%F A084158 a(n)=((sqrt(2)+1)^(2n+1)-(sqrt(2)-1)^(2n+1)-2(-1)^n)/16.
%F A084158 a(n) = 5*a(n-1) + 5*a(n-2) - a(n-3). - Mohamed Bouhamida (bhmd95(AT)yahoo.fr), 
               Sep 02 2006; corrected by Antonio A. Olivares (olivares14031(AT)yahoo.com), 
               Mar 29 2008
%F A084158 a(n) = (-1/8)*(-1)^n + (( sqrt(2)+1)/16)*(3+2*sqrt(2))^n + ((-sqrt(2)+1)/
               16)*(3-2*sqrt(2))^n. - Antonio A. Olivares (olivares14031(AT)yahoo.com), 
               Mar 30 2008
%F A084158 (a(n)-a(n-1))^(1/2) = A000129(n) - Antonio A. Olivares (olivares14031(AT)yahoo.com), 
               Mar 30 2008
%F A084158 O.g.f.: x/((1+x)(x^2-6*x+1)). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               May 18 2008
%F A084158 a(n)=A041011(n)*A041011(n+1). - R. Guy (rkg(AT)cpsc.ucalgary.ca), May 
               18 2008
%F A084158 a(n)=6*a(n-1)-a(n-2)-(-1)^n. a(n)=7*(a(n-1)-a(n-2))+a(n-3)-2*(-1)^n. 
               - Mohamed Bouhamida (bhmd95(AT)yahoo.fr), Aug 30 2008
%p A084158 with(combinat): a:=n->fibonacci(n,2)*fibonacci(n-1,2)/2: seq(a(n), n=1..22); 
               - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 04 2008
%Y A084158 Cf. A084159, A084175, A001654.
%Y A084158 Cf. a001652.
%Y A084158 Sequence in context: A003731 A055838 A094972 this_sequence A111469 A057088 
               A156195
%Y A084158 Adjacent sequences: A084155 A084156 A084157 this_sequence A084159 A084160 
               A084161
%K A084158 easy,nonn
%O A084158 0,3
%A A084158 Paul Barry (pbarry(AT)wit.ie), May 18 2003