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%I #9 Mar 21 2021 12:08:47
%S 3,3,9,9,50,50,204,204,1135,1135,6086,6086,36018,36018,216932,216932,
%T 1306070,1306070,8129138,8129138,51773946,51773946,326701423,326701423
%N Total number of palindromic primes in base 7 below 7^n.
%C Every palindrome with an even number of digits is divisible by 11 (in base 7) and therefore is composite (not prime). Hence there is no palindromic prime with an even number of digits.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PalindromicPrime.html">Palindromic Prime</a>.
%Y Partial sums of A117784.
%Y Cf. A029975, A117702.
%Y Cf. A117772, A117775, A117777, A117779, A117781, A117785, A117787.
%K nonn,base,more
%O 1,1
%A _Martin Renner_, Apr 15 2006
%E a(9)-a(24) from the data at A117784 added by _Amiram Eldar_, Mar 21 2021
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