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 A121267 #30 Jul 05 2025 16:29:08 %S A121267 1,5,1,3,1,2,1,4,3057,2,3,14650,4,2,46,4 %N A121267 Number of decimal digits in A047777(n). %C A121267 Not equal to the first differences of A053013 (which is based on a different variant of A047777). %C A121267 "A new visitor to an old problem! Jens Kruse Andersen confirmed the primality of Nash's 3057-digit prime using PRIMO." - _Carlos Rivera_, Sep 2002 %C A121267 If it exists, then a(17) > 50000. - _Lucas A. Brown_, Jul 04 2024 %H A121267 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A121267.py">Python program</a>. %H A121267 Carlos Rivera, <a href="http://www.primepuzzles.net/problems/prob_018.htm">Problem 18. Pi as a concatenation of the smallest contiguous different primes</a>, The Prime Puzzles & Problems Connection. %o A121267 (PARI) default(realprecision,5000);c=Pi/10;u=[];for(k=1,9e9,ispseudoprime(c\.1^k) & !setsearch(u,c\.1^k) & (u=setunion(u,Set(c\.1^k))) & !print1(k,",") & k=0*c=frac(c*10^k)) \\ _M. F. Hasler_, Sep 15 2013 %Y A121267 Cf. A047777, A053013. %K A121267 nonn,base,more,hard %O A121267 1,2 %A A121267 _Robert G. Wilson v_, Aug 23 2006 %E A121267 The old values a(10) onwards were incorrect, as discovered by _M. F. Hasler_, Aug 31 2013. The old values, the b-file and the Mathematica program have been deleted. - _N. J. A. Sloane_, Sep 01 2013