Non-cubefree numbers k such that 2k+1 is also non-cubefree (A046099).

Terms

a(0) =40a(1) =256a(2) =312a(3) =472a(4) =688a(5) =904a(6) =1120a(7) =1200a(8) =1312a(9) =1336a(10) =1552a(11) =1768a(12) =1984a(13) =2187a(14) =2200a(15) =2312a(16) =2416a(17) =2456a(18) =2632a(19) =2848a(20) =2875a(21) =3064a(22) =3280a(23) =3312a(24) =3429a(25) =3496a(26) =3712a(27) =3928a(28) =3944a(29) =4144