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Decimal expansion of Pi/2 truncated to n places.
1

%I #15 Jan 12 2022 17:06:35

%S 1,15,157,1570,15707,157079,1570796,15707963,157079632,1570796326,

%T 15707963267,157079632679,1570796326794,15707963267948,

%U 157079632679489,1570796326794896,15707963267948966,157079632679489661,1570796326794896619,15707963267948966192

%N Decimal expansion of Pi/2 truncated to n places.

%F a(n) = floor((1/2)*Pi*10^n), Pi = 3.14159265...

%p seq(floor(1/2*Pi*10^n),n=0..19);

%t Array[Floor[10^#*Pi/2] &, 20, 0] (* _Michael De Vlieger_, Feb 25 2018 *)

%t Module[{nn=30,pi2},pi2=RealDigits[Pi/2,10,nn][[1]];Table[FromDigits[ Take[ pi2,n]],{n,nn}]] (* _Harvey P. Dale_, Jan 12 2022 *)

%Y Cf. A011545, A019669.

%K nonn,base,easy,less

%O 1,2

%A _Martin Renner_, Feb 24 2018