%I #22 Nov 09 2019 03:14:03
%S 3,5,21,33,401,563,7017,37685
%N Numbers k such that (14*10^(k-1) - 41)/9 is a plateau prime.
%C Prime versus probable prime status and proofs are given in the author's table.
%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/deplat.htm#pdp151">PDP Reference Table - 151</a>.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/1/15551.htm#prime">Prime numbers of the form 155...551</a>.
%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F a(n) = A056246(n+1) + 2.
%e k=21 -> (14*10^(21-1) - 41)/9 = 155555555555555555551.
%Y Cf. A056246, A068646, A082697-A082720.
%K nonn,base,more
%O 1,1
%A _Patrick De Geest_, Apr 13 2003
%E 37685 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
%E Edited by _Ray Chandler_, Nov 04 2014