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 A169984 #7 Mar 30 2012 17:38:11 %S A169984 51,52,53,54,56,57,58,59,551,553,557,559,5051,5053,5057,5059,5501, %T A169984 5503,5507,5509,50051,50053,50057,50059,55001,55003,55007,55009,55551, %U A169984 55553,55557,55559,500501,500503,500507,500509,505001,505003 %N A169984 Primes in carryless arithmetic mod 10 in which all digits except the rightmost are zero or five. %C A169984 These are called f-type primes. %H A169984 <a href="/index/Ca#CARRYLESS">Index entries for sequences related to carryless arithmetic</a> %Y A169984 A169887 = A163396 union A169984. %K A169984 nonn,base %O A169984 1,1 %A A169984 _David Applegate_, _Marc LeBrun_ and _N. J. A. Sloane_, Aug 24 2010