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 A070154 #14 Apr 29 2022 12:01:34 %S A070154 1,3,4,9,5,9,14,10,10,19,16,21,22,22,24,20,19,24,28,28,29,30,39,31,44, %T A070154 40,44,33,41,47,44,48,54,48,60,49,63,51,65,72,64,70,78,64,79,77,74,87, %U A070154 75,86,82,94,88,106,106,94,104,108,87,107,86,106,98,110,115,110,105,115 %N A070154 Number of terms in the simple continued fraction expansion of Sum_{k=0..n}(-1)^k/(2k+1), the Leibniz-Gregory series for Pi/4. %C A070154 Pi/4 = Sum_{k=>0} (-1)^k/(2k+1). %H A070154 Amiram Eldar, <a href="/A070154/b070154.txt">Table of n, a(n) for n = 0..10000</a> %F A070154 Limit_{n -> infinity} a(n)/n = C = 1.6... %e A070154 The simple continued fraction for Sum(k=0,10,(-1)^k/(2k+1)) is [0, 1, 4, 4, 1, 3, 54, 1, 2, 1, 1, 4, 11, 1, 2, 2] which contains 16 elements, hence a(10)=16. %t A070154 lcf[f_] := Length[ContinuedFraction[f]]; lcf /@ Accumulate[Table[(-1)^k/(2*k + 1), {k, 0, 100}]] (* _Amiram Eldar_, Apr 29 2022 *) %o A070154 (PARI) for(n=1,100,print1( length(contfrac(sum(i=0,n,(-1)^i/(2*i+1)))),",")) %Y A070154 Cf. A003881, A007509, A055573, A069880, A069887. %K A070154 easy,nonn %O A070154 0,2 %A A070154 _Benoit Cloitre_, May 06 2002 %E A070154 Offset changed to 0 and a(0) inserted by _Amiram Eldar_, Apr 29 2022