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 A083808 #11 Jul 02 2025 16:02:02 %S A083808 2,23,223,24443,199999,666667,19999999,22222223,666666667,44444444441, %T A083808 22222222223,2444444444443,17777777777777,88888888888889, %U A083808 1333333333333333,64444444444444439,88888888888888889 %N A083808 Smallest prime == 1 (mod n-th unary number U(n) = (10^n-1)/9). %e A083808 a(4) = 24443 ==1 (mod 1111). %p A083808 with(numtheory): for n from 1 to 30 do u := (10^n-1)/9: for j from u+1 to 1000*u+1 by u do if isprime(j) then printf(`%d,`,j); break; fi: od:od: %Y A083808 Cf. A000042. %K A083808 base,nonn %O A083808 1,1 %A A083808 _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003 %E A083808 Corrected and extended by _James Sellers_, May 19 2003