|
%I #19 Nov 10 2019 01:32:50
%S 7,9,895,1525,3037,21157
%N Numbers k such that (29*10^(k-1) + 7)/9 is a depression 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#pdp323">PDP Reference Table - 323</a>.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/3/32223.htm#prime">Prime numbers of the form 322...223</a>.
%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F a(n) = A056252(n) + 2.
%e k=9 -> (29*10^(9-1) + 7)/9 = 322222223.
%Y Cf. A082697-A082720, A056252.
%K nonn,base,hard,more
%O 1,1
%A _Patrick De Geest_, Apr 13 2003
%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
%E Edited by _Ray Chandler_, Nov 05 2014
| 