Alternated reading of A000302 and negated A002042.

Terms

a(0) =1a(1) =-7a(2) =4a(3) =-28a(4) =16a(5) =-112a(6) =64a(7) =-448a(8) =256a(9) =-1792a(10) =1024a(11) =-7168a(12) =4096a(13) =-28672a(14) =16384a(15) =-114688a(16) =65536a(17) =-458752a(18) =262144a(19) =-1835008a(20) =1048576a(21) =-7340032a(22) =4194304a(23) =-29360128a(24) =16777216a(25) =-117440512a(26) =67108864a(27) =-469762048a(28) =268435456a(29) =-1879048192