%I A042981
%S A042981 1,0,1,1,1,3,4,8,15,24,48,85,155,297,541,1024,1935,3626,6912,13107,
%T A042981 24940,47709,91136,174760,335626,645120,1242904,2396745,4627915,
%U A042981 8948385,17317888,33554432
%N A042981 Number of degree-n irreducible polynomials over GF(2) with trace = 1 
               and subtrace = 0.
%D A042981 K. Cattell, C.R. Miers, F. Ruskey, J. Sawada and M. Serra, "The Number 
               of Irreducible Polynomials over GF(2) with Given Trace and Subtrace", 
               J. Comb. Math. and Comb. Comp., 47 (2003) 31-64.
%H A042981 F. Ruskey, <a href="http://www.theory.cs.uvic.ca/~cos/inf/neck/TraceSubtracePoly.html">
               Number of irreducible polynomials over GF(2) with given trace and 
               subtrace</a>
%F A042981 a(n) = Sum{ L(n, k) : n+k = 2 mod 4}, where L(n, k) = Sum{ mu(d)*{n/d 
               choose k/d} : d|gcd(n, k)}
%Y A042981 Cf. A042979-A042982.
%Y A042981 Cf. A074027-A074030.
%Y A042981 Sequence in context: A026654 A104370 A033854 this_sequence A007486 A027977 
               A165438
%Y A042981 Adjacent sequences: A042978 A042979 A042980 this_sequence A042982 A042983 
               A042984
%K A042981 nonn
%O A042981 1,6
%A A042981 Frank Ruskey (fruskey(AT)cs.uvic.ca)