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Numbers k such that the smoothly undulating palindromic number (38*10^k - 83)/99 is a prime.
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%I #17 Aug 11 2024 14:41:34

%S 3,9,15,17,21,57,4233,4335,13221,26447,29897,91997

%N Numbers k such that the smoothly undulating palindromic number (38*10^k - 83)/99 is a prime.

%C Prime versus probable prime status and proofs are given in the author's table.

%C No further terms < 100000. - _Ray Chandler_, Aug 17 2011

%H P. De Geest, <a href="https://www.worldofnumbers.com/undulat.htm#supp383">SUPP Reference Table - 383</a>

%H <a href="/index/Pri#pri_supp">Index entries for sequences related to smoothly undulating palindromic primes</a>

%e k=21 -> (38*10^21 - 83)/99 = 383838383838383838383.

%Y Cf. A062209-A062232, A059758, A032758.

%K nonn,base

%O 1,1

%A _Patrick De Geest_ and Hans Rosenthal (Hans.Rosenthal(AT)t-online.de), Jun 15 2001

%E a(12)=91997 from _Ray Chandler_, Jul 29 2011

%E Edited by _Ray Chandler_, Aug 17 2011