%I #13 Nov 11 2019 21:46:46
%S 3,5,7,9,11,13,15,17,19,21,23,29,31,33,37,41,49,53,55,59,61,65,67,69,
%T 73,75,83,85,87,93,95,97,101,103,105,111,113,115,117,121,127,129,141,
%U 157,161,171,193,201,205,209,231,247,291,323,343,351,353,361,367,401
%N Digit lengths for which there exist plateau or depression primes of the general form a*(10^m-1)/9 +- b*(10^(m-1)+1).
%D C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
%H Patrick De Geest, <a href="http://www.worldofnumbers.com/pdpsorted.htm">PDP's Sorted By Length</a>
%Y Cf. A082697-A082719, A077797, A077799.
%K nonn,base
%O 0,1
%A _Patrick De Geest_, Apr 13 2003