%I A140505
%S A140505 2,1,4,0,12,4,44,20,172,84,684,340,2732,1364,10924,5460,43692,21844,174764,
               87380,
%T A140505 699052,349524,2796204,1398100,11184812,5592404,44739244,22369620,178956972,
               89478484,
%U A140505 715827884,357913940,2863311532,1431655764,11453246124
%V A140505 2,-1,4,0,12,4,44,20,172,84,684,340,2732,1364,10924,5460,43692,21844,174764,
               87380,
%W A140505 699052,349524,2796204,1398100,11184812,5592404,44739244,22369620,178956972,
               89478484,
%X A140505 715827884,357913940,2863311532,1431655764,11453246124
%N A140505 Second differences of Jacobsthal sequence A001045, pairs with even and 
               odd indices swapped.
%C A140505 The second differences are -1, 2, 0, 4, 4, 12, 20, 44, ... (-1)^(n+1)*A084247(n), 
               essentially A097073, which are listed here with -1 <=> 2, 0 <=> 4 
               etc. swapped in pairs.
%F A140505 a(n) = 4*A092808(n-2), n>1.
%F A140505 a(n+1) - 2a(n) = (-1)^n*A140504(n).
%F A140505 O.g.f.: (2+x-5x^2)/[(1+x)(1-2x)(1+2x)]. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Jul 08 2008
%Y A140505 Sequence in context: A077979 A122161 A067164 this_sequence A117971 A131642 
               A070674
%Y A140505 Adjacent sequences: A140502 A140503 A140504 this_sequence A140506 A140507 
               A140508
%K A140505 sign,less
%O A140505 0,1
%A A140505 Paul Curtz (bpcrtz(AT)free.fr), Jun 30 2008
%E A140505 Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 08 2008