a(0) = 4; to obtain a(k), write out the base-(2^k) expansion of a(k-1), bump to base 2^(k+1), then subtract 1.

A372237

a(0) = 4; to obtain a(k), write out the base-(2^k) expansion of a(k-1), bump to base 2^(k+1), then subtract 1.

Terms

    a(0) =4a(1) =15a(2) =26a(3) =49a(4) =96a(5) =191a(6) =318a(7) =573a(8) =1084a(9) =2107a(10) =4154a(11) =8249a(12) =16440a(13) =32823a(14) =65590a(15) =131125a(16) =262196a(17) =524339a(18) =1048626a(19) =2097201a(20) =4194352a(21) =8388655a(22) =16777262a(23) =33554477a(24) =67108908a(25) =134217771a(26) =268435498a(27) =536870953a(28) =1073741864a(29) =2147483687

External references