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Central digit of palindromic primes.
0

%I #8 Aug 11 2024 14:41:34

%S 0,3,5,8,9,1,5,7,8,2,5,8,9,1,2,3,5,6,3,4,4,7,8,3,8,9,3,7,4,5,0,3,5,6,

%T 4,9,1,4,3,8,9,1,2,4,7,8,0,5,3,4,5,5,8,0,1,3,7,2,5,2,5,0,1,7,2,2,5,6,

%U 3,9,2,7,0,2,6,0,7,5,3,6,3,4,9,4,7,8,3,6,9,7,0,1,2,7,0,3,6,8,9,9,2,4,7,3,5

%N Central digit of palindromic primes.

%C Middle digit of terms of A002385 from 101 onwards, skipping 2, 3, 5, 7, 11 hence offset starting at 6.

%H P. De Geest, <a href="https://www.worldofnumbers.com/em_palpri.htm">World!Of Palindromic Primes</a>

%t a = {}; Do[pp = IntegerDigits[ Prime[n]]; If[pp == Reverse[pp], a = Append[a, pp[[(Length[pp] + 1)/2]]]], {n, 6, 9385}]; a

%Y Cf. A002385.

%K base,nonn

%O 6,2

%A _Amarnath Murthy_, Nov 08 2002

%E Edited and extended by _Patrick De Geest_, Jun 11 2003

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Last modified September 24 07:26 EDT 2024. Contains 376187 sequences. (Running on oeis4.)