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 A053748 #29 May 31 2021 09:03:39 %S A053748 3,20,24,37,58,60,61,71,88,93,105,120,126,127,146,152,158,163,183,184, %T A053748 189,193,202,203,218,219,224,228,252,255,263,267,272,274,279,294,297, %U A053748 304,322,340,349,372,377,385,387 %N A053748 Positions of 4's in the decimal expansion of Pi. %H A053748 Vincenzo Librandi, <a href="/A053748/b053748.txt">Table of n, a(n) for n = 1..1000</a> %H A053748 <a href="/index/Ph#Pi314">Index entries for sequences related to the number Pi</a> %F A053748 a(n) = A037003(n) + 1. - _Georg Fischer_, May 31 2021 %e A053748 Pi starts off 3.141592653589793238462643383279502884197..., with 4s in the hundredths' (10^(-2)s') place, which is the third digit counting the 3 in the ones' place. Then there's another 4 at the 10^(-19)s' place, which is the twentieth digit counting the initial 3. [_Alonso del Arte_, Oct 07 2013] %t A053748 Flatten[Position[RealDigits[Pi, 10, 1000][[1]], 4]] (* _Vincenzo Librandi_, Oct 07 2013 *) %Y A053748 Cf. A000796, A037003. %K A053748 nonn,base %O A053748 1,1 %A A053748 _Simon Plouffe_, Feb 20 2000