%I A007751
%S A007751 0,7,120,1921,30624,488071,7778520,123968257,1975713600,31487449351,
%T A007751 501823476024,7997688167041,127461187196640,2031381306979207,
%U A007751 32374639724470680,515962854284551681,8223031028828356224
%N A007751 Even bisection of A007750.
%D A007751 Mentioned in a problem on p. 334 of Two-Year College Math. Jnl., Vol. 
               25, 1994.
%F A007751 G.f.: x(7+x)/((1-x)(1-16x+x^2)). a(n)=16a(n-1)-a(n-2)+8.
%F A007751 a(n)=-4/7+(2/7)*[8-3*sqrt(7)]^n+(2/7)*[8+3*sqrt(7)]^n+(1/14)*sqrt(7)*[8+3*sqrt(7)]^n-(1/
               14) *[8-3*sqrt(7)]^n*sqrt(7), with n>=0 - Paolo P. Lava (ppl(AT)spl.at), 
               Jun 19 2008
%o A007751 (PARI) a(n)=local(w); w=8+3*quadgen(28); imag(w^n)+4*(real(w^n)-1)/7
%Y A007751 Cf. A007750, A007752.
%Y A007751 Sequence in context: A057769 A113667 A092612 this_sequence A156955 A095752 
               A113267
%Y A007751 Adjacent sequences: A007748 A007749 A007750 this_sequence A007752 A007753 
               A007754
%K A007751 nonn
%O A007751 0,2
%A A007751 John C. Hallyburton, Jr. [ hallyb(AT)vmsdev.enet.dec.com ].
%E A007751 Edited by Michael Somos, Jul 27, 2002