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 A282183 #49 Mar 26 2025 19:30:57
%S A282183 1,2,5,6,7,11,15,712,7599,13280,13281,21598,23233
%N A282183 Numbers k such that the reverse of the first k digits in the decimal expansion of Pi forms a prime.
%C A282183 The initial digits of a few corresponding primes are in A007523. The last one a(10)=768556......62951413 is a prime with 13280-digit. That is A092845(13279).
%C A282183 a(14) > 50000. - _Michael S. Branicky_, Feb 06 2025
%H A282183 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_19">Mystery of pi</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 19, 473-497.
%e A282183 1 is a term as the first digit of pi, 3, reversed is prime. 2 is a term as the first two digits of pi, 31, reversed is prime. 3 is not a term as the first three digits of pi, 314, reversed, is not prime. - _David A. Corneth_, Feb 13 2017
%t A282183 Do[If[PrimeQ[FromDigits[Reverse[IntegerDigits[Floor[Pi*10^(n - 1)]]]]],Print[n]],{n, 13335}]
%t A282183 Module[{pid=RealDigits[Pi,10,20000][[1]]},Select[Range[16000],PrimeQ[ FromDigits[ Reverse[Take[pid,#]]]]&]] (* _Harvey P. Dale_, Sep 06 2019 *)
%Y A282183 Cf. A092845, A007523, A011545.
%K A282183 nonn,more,base,less
%O A282183 1,2
%A A282183 _XU Pingya_, Feb 13 2017
%E A282183 a(11)-a(13) from _Michael S. Branicky_, Feb 06 2025