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 A266368 #27 Jul 23 2025 15:39:35
%S A266368 11,1231,149161,181,1168125662512961,1321,1647294096156251,
%T A266368 11282187163847812527993682354320971524782969100000001948717135831808627485171,
%U A266368 125665616553639062516796161,15121
%N A266368 The smallest prime formed by the concatenation of consecutive n-th powers beginning with "1," plus a trailing "1.".
%C A266368 a(10) has 437 and a(11) has 1810 decimal digits respectively. - _Michael De Vlieger_, Jan 05 2016
%C A266368 a(13) is a bit more manageable, with 65 decimal digits - 18192159432367108864122070312513060694016968890104075497558138881. a(14) and a(15) are even shorter, with 23 and 15 decimal digits, respectively - 11638447829692684354561 and 132768143489071. - _Thomas S. Pedigo_, Jan 06 2016
%e A266368 a(6)=1647294096156251; 1=1^6; 64=2^6; 729=3^6; 4096=4^6; 15625=5^6; 1647294096156251 is prime.
%t A266368 f[k_, n_] := FromDigits@ Flatten@ Map[IntegerDigits, Append[Range[k + 1]^n, 1], 1]; Table[If[n == 0, k = 0, k = 1]; While[! PrimeQ@ f[k, n], k++]; f[k, n], {n, 0, 9}] (* _Michael De Vlieger_, Jan 05 2016 *)
%Y A266368 Cf. A019521, A019522.
%K A266368 nonn,base
%O A266368 0,1
%A A266368 _Thomas S. Pedigo_, Dec 28 2015