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 A229155 #22 Mar 26 2020 09:01:22 %S A229155 1,1,649,1,1,2,29,1,1,2,1,1,1,53,1872,3,5 %N A229155 Number of digits of the n-th term of the decimal expansion of e = exp(1) cut into chunks of primes. %C A229155 Trying to cut the decimal expansion A001113 of e=2.718281828... into "prime chunks", one gets (2, 7, p, 5, 3, 11, q, 7, 3, 61, 3, 3, 2, r, ...) where p, q, r are 649-, 29-, 53-digit primes, respectively. The size of p makes it impossible to register this more fundamental sequence in the OEIS as it is done in A047777 for Pi. This led us to store just the length of the terms in this sequence. %C A229155 Sequence A121267 is a (not exact) analog for Pi; note that A047777 requires all primes to be distinct, while we allow repetition of 7, 3, 2, ... as seen in the above example. If we did not, the terms following 29 would be 2, 2, 6, 3, 7, 8, 3, 441, 9, 17, ... instead of 1, 1, 2, 1, 1, 1, 53, ... %H A229155 Joseph L. Pe, <a href="http://web.archive.org/web/20090902201007/http://geocities.com/windmill96/primegen/eprimes.html">Trying to Write e as a Concatenation of Primes</a> (2009) %o A229155 (PARI) default(realprecision,2000);c=exp(1)/10;for(k=1,9e9,ispseudoprime(c\.1^k) & !print1(k,",") & k=0*c=frac(c*10^k)) %Y A229155 Cf. A007512, A001113, A047658, A064118. %K A229155 nonn,base,more %O A229155 1,3 %A A229155 _M. F. Hasler_, Sep 15 2013 %E A229155 a(15)-a(17) from _Jinyuan Wang_, Mar 26 2020