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 A082521 #20 Apr 17 2025 09:55:24 %S A082521 101,1300031,140000041,19000000091,1300000000031,140000000000041, %T A082521 16000000000000061,7100000000000000017,340000000000000000043, %U A082521 35000000000000000000053,7400000000000000000000047,940000000000000000000000049,13000000000000000000000000031 %N A082521 Least palindromic prime with at least 2n+1 central 0's. %C A082521 Each term has 2n+1 central 0s but it can occur that there are some more 0s adjacent to them. In such cases, successive terms of this sequence are identical. This can be seen in the b-file at n = 20, 40, 54, 66, 80, 97, 146, ... - _Jeppe Stig Nielsen_, Apr 04 2025 %H A082521 Jeppe Stig Nielsen, <a href="/A082521/b082521.txt">Table of n, a(n) for n = 0..450</a> %o A082521 (PARI) A082521(n)=forstep(j=10^(n+1),+oo,10^(n+1),my(d=digits(j), p=fromdigits(vector(2*#d-1,k,if(k<#d,d[k],d[2*#d-k])))); ispseudoprime(p)&&return(p)) \\ _Jeppe Stig Nielsen_, Apr 04 2025 %Y A082521 Cf. A002385, A028989, A098045. %K A082521 base,nonn %O A082521 0,1 %A A082521 _Lekraj Beedassy_, Apr 30 2003 %E A082521 More terms from _Joshua Zucker_, May 11 2006 %E A082521 a(12) from _Jeppe Stig Nielsen_, Apr 04 2025