Sorry but I couldn't resist.

#!/usr/bin/perl

$|=1;$N=shift||100;$M=int(3.3*$N)
;$t[0]=2;$s[0]=2;sub z{$a=$r=00};
for(                         $k=1
;$k<$M   ;$k++){$a=$r=0;   };for(
$k=01;   $k<$M;$k++){&z;   for($i
=$N;$i   >=0;$i--){$a=$t   [$i]*(
$k)+$r   ;$t[$i]=int($a%   10);${
r}=int   ($a/10);}$K=($k   <<1)+1
;&{z};   map{$a=$t[$_]+(   10)*((
$r));;   ${t}[$_]=int($a   /($K))
;${r}=   int(($a)%($K))}   (0..$N
);if((   $r>=(int(($K)/2   )))){;
;;${t}   [$N]++}while($t   [$N]>9
){${t}   [$N]-=10;;$t[$N   -1]++}
&z();   for($i=$N;$i>=0   ;$i--){
$a=    ($t[$i]+$s[$i]+   $r);${s}
[$i]=int($a%10);$r=int($a/10)}if(
$k>$x+3){${x}=$k;;print"$s[$y++]"
;};}for($y..${N}){print"$s[$_]";}
[download]

You can pass the desired number of digits as parameter on the commandline.

Of course the method used was choosed more for its simplicity than for its speed.
(But this code could be optimized several ways, by adding 'use integer;' for example...)

For REAL program you should use Math::GMP or Math::Float and real formulae
(Gregory,Machin,Ramanadjuan...)

Any search on the net would give you a lot of start point, you might try this one.


"Trying to be a SMART lamer" (thanx to Merlyn ;-)