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Triangle of numbers obtained by reversing the first n digits of 1/Pi and juxtaposing.
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%I #3 Jun 28 2012 12:30:46

%S 0,3,0,1,3,0,8,1,3,0,3,8,1,3,0,0,3,8,1,3,0,9,0,3,8,1,3,0,8,9,0,3,8,1,

%T 3,0,8,8,9,0,3,8,1,3,0,6,8,8,9,0,3,8,1,3,0,1,6,8,8,9,0,3,8,1,3,0,8,1,

%U 6,8,8,9,0,3,8,1,3,0,3,8,1,6,8,8,9,0,3,8,1,3,0,7,3,8,1,6,8,8,9,0,3,8,1,3,0

%N Triangle of numbers obtained by reversing the first n digits of 1/Pi and juxtaposing.

%e 0; 3,0; 1,3,0; 8,1,3,0; 3,8,1,3,0;... (reverse order of 0; 0.3; 0.31; 0.318; 0.3183;...)

%t With[{d=Join[{0},RealDigits[1/Pi,10,30][[1]]]},Flatten[Table[Reverse[ Take[d,n]],{n,20}]]] (* _Harvey P. Dale_, Jun 28 2012 *)

%o (PARI) a(n)=if(n<1,0,default(realprecision,n+2);floor(1/Pi*10^(n-1))%10); b(n)=1+binomial(1+floor(1/2+sqrt(2*n)),2)-n; for(n=1,120,print1(a(b(n)),",")

%Y Cf. A049541.

%K base,easy,nonn,tabl

%O 1,2

%A Herman Jamke (hermanjamke(AT)fastmail.fm), Jul 07 2004