A260685(4n).

Terms

a(0) =-2a(1) =-6a(2) =4a(3) =-54a(4) =28a(5) =132a(6) =124a(7) =-4470a(8) =444a(9) =5964a(10) =2044a(11) =89028a(12) =8188a(13) =248172a(14) =9784a(15) =-30229110a(16) =131068a(17) =7314348a(18) =524284a(19) =361466316a(20) =174136a(21) =354424812a(22) =8388604a(23) =54096506052a(24) =16344060a(25) =12926541804a(26) =46427196a(28) =536870908a(29) =216322653432