This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A154956 #19 Nov 24 2020 15:52:48
%S A154956 1,2,3,5,10,71,868,1788,7455,44266,54626,74153,224166,390471,1489304,
%T A154956 3737961,22277163,37201631,113275744,165029426,2642368758,3362202939,
%U A154956 5191046363,8438525012,36226438506,40174126779,125336047846,531802867080,599020778171
%N A154956 Pierce expansion of 2/Pi.
%H A154956 Simon Plouffe and G. C. Greubel, <a href="/A154956/b154956.txt">Table of n, a(n) for n = 0..500</a> (terms from 0 to 216 were computed by Simon Plouffe)
%e A154956 1 - 1/2(1 - 1/3(1 - 1/5(1 - 1/10(1 - 1/71)))) = 2/(355/113).
%p A154956 Digits := 300: Pierce := proc(x) local resid,a,i,an ; resid := x ; a := [] ; for i from 1 do an := floor(1./resid) ; a := [op(a),an] ; resid := evalf(1.-an*resid) ; if ilog10( mul(i,i=a)) > 0.7*Digits then break ; fi ; od: RETURN(a) ; end: a060294 := evalf(2/Pi) ; Pierce(a060294) ; # _R. J. Mathar_, Jan 21 2009
%t A154956 PierceExp[A_, n_] := Join[Array[1 &, Floor[A]], First@Transpose@ NestList[{Floor[1/Expand[1 - #[[1]] #[[2]]]], Expand[1 - #[[1]] #[[2]]]} &, {Floor[1/(A - Floor[A])], A - Floor[A]}, n - 1]]; PierceExp[N[2/Pi, 7!], 50] (* _G. C. Greubel_, Nov 13 2016 *)
%o A154956 (PARI) A154956(N=99)={localprec(N); my(c=2/Pi, d=c+c/10^N, a=[1\c]); while(a[#a]==1\d&&c=1-c*a[#a], d=1-d*a[#a]; a=concat(a, 1\c)); a[^-1]} \\ The optional argument is the precision used, approx. equal to the total number of digits in the result. - _M. F. Hasler_, Jul 04 2016
%Y A154956 Cf. A006283 (1/Pi), A061233 (4 - Pi).
%Y A154956 Cf. A060294 (decimal expansion of 2/Pi). - _R. J. Mathar_, Jan 21 2009
%K A154956 nonn
%O A154956 0,2
%A A154956 _Jaume Oliver Lafont_, Jan 18 2009
%E A154956 More terms from _R. J. Mathar_, Jan 21 2009
%E A154956 Offset in b-file corrected by _N. J. A. Sloane_, Aug 31 2009