A121349 - OEIS

%I #30 Aug 31 2021 12:45:08

%S 1,3,6,13,25,50,101,201,402,804,1608,3217,6434,12868,25736,51472,

%T 102944,205887,411775,823550,1647099,3294199,6588397,13176795,

%U 26353589,52707179,105414357,210828714,421657428,843314857,1686629713,3373259426

%N a(n) = round(Pi*2^(n-1)) for n >= 1, a(0) = 1.

%C As n approaches infinity, the distance between the center and each vertex of a regular polygon with a(n) sides of unit length approaches 2^(n-2) units. - _Ahmad J. Masad_, Jul 02 2021

%t Table[FromDigits[RealDigits[Pi, 2, k][[1]], 2], {k, 1, 50}]

%o (PARI) a(n) = if(n<1, 1, round(Pi*2^(n-1))); \\ _Michel Marcus_, Jul 02 2021

%Y Cf. A004601, A068425, A155996, A293342.

%K nonn,easy,less

%O 0,2

%A _Carlos Alves_, Jul 22 2006

%E Better definition from _Jon E. Schoenfield_, Jan 17 2015

%E Definition amended by _Georg Fischer_, Aug 31 2021