Positions of the first n-bit number to appear in Van Eck's sequence (A181391).

Terms

a(0) =1a(1) =5a(2) =10a(3) =24a(4) =41a(5) =52a(6) =152a(7) =162a(8) =364a(9) =726a(10) =1150a(11) =2451a(12) =4626a(13) =9847a(14) =18131a(15) =36016a(16) =71709a(17) =143848a(18) =276769a(19) =551730a(20) =1086371a(21) =2158296a(22) =4297353a(23) =8607525a(24) =17159741a(25) =34152001a(26) =68194361a(27) =136211839a(28) =271350906a(29) =541199486