%I A074081
%S A074081 4,1,3,7,15,26,51,99,191,367,708,1365,2631,5071,9775,18842,36319,70007,
%T A074081 134943,260111,501380,966441,1862875,3590807,6921503,13341626,25716811,
               49570747,
%U A074081 95550687,184179871,355018116,684319421,1319068095,2542585503,4900991135
%V A074081 4,-1,3,-7,15,-26,51,-99,191,-367,708,-1365,2631,-5071,9775,-18842,36319,
               -70007,
%W A074081 134943,-260111,501380,-966441,1862875,-3590807,6921503,-13341626,25716811,
               -49570747,
%X A074081 95550687,-184179871,355018116,-684319421,1319068095,-2542585503,4900991135
%N A074081 Sum of determinants of 3rd order principal minors of powers of inverse 
               of tetramatrix ((1,1,0,0),(1,0,1,0),(1,0,0,1),(1,0,0,0)).
%C A074081 a(n)=(-1)^nT(n), where T(n) are the generalized tetranacci numbers A073817
%F A074081 a(n)=-a(n-1)+a(n-2)-a(n-3)+a(n-4), a(0)=4, a(1)=-1, a(2)=3, a(3)=-7. 
               G.f.: (4+3x-2x^2+x^3)/(1+x-x^2+x^3-x^4).
%t A074081 CoefficientList[Series[4+3*x-2*x^2+x^3)/(1+x-x^2+x^3-x^4), {x, 0, 40}], 
               x]
%Y A074081 Cf. A000078, A001630, A073817 (another version), A073937.
%Y A074081 Sequence in context: A151861 A109531 A073817 this_sequence A132703 A154182 
               A093735
%Y A074081 Adjacent sequences: A074078 A074079 A074080 this_sequence A074082 A074083 
               A074084
%K A074081 easy,sign
%O A074081 0,1
%A A074081 Mario Catalani (mario.catalani(AT)unito.it), Aug 19 2002