%I #15 Mar 26 2023 12:45:25
%S 0,2,5,33,8589934593
%N a(0) = 0; for n >= 0, a(n+1) = 2^a(n) + 1.
%F a(n+1) = A000051(a(n)). - _Reinhard Zumkeller_, Jan 31 2015
%t RecurrenceTable[{a[0]==0, a[n]==2^a[n-1] + 1}, a, {n, 5}] (* _Vincenzo Librandi_, Feb 01 2015 *)
%t NestList[2^#+1&,0,4] (* _Harvey P. Dale_, Mar 26 2023 *)
%o (Haskell)
%o a254429 n = a254429_list !! n
%o a254429_list = iterate ((+ 1) . (2 ^)) 0
%o -- _Reinhard Zumkeller_, Jan 31 2015
%o (Magma) [n le 2 select 2*(n-1) else 2^Self(n-1)+1: n in [1..5]]; // _Vincenzo Librandi_, Feb 01 2015
%Y Cf. A007013, A254411.
%Y Cf. A000051.
%K nonn
%O 0,2
%A _Max Alekseyev_, Jan 30 2015