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%I #7 May 25 2019 11:04:53
%S 1,1,1,3,1,7,1,9,2,3,2,9,3,1,3,7,4,1,4,3,4,7,5,3,5,9,6,1,6,7,7,1,7,3,
%T 7,9,8,3,8,9,9,7,0,0,0,1,0,1,0,2,0,3,0,3,0,3,0,4,0,5,0,6,0,6,0,6,0,8,
%U 0,9,0,9,0,9,1,0,1,0,1,1,1,2,1,2,1,5,1,5,1,6,1,7,1,8,1,8,1,9,2,0,2,1,2,1,2
%N The pairs of central digits of all primes with an even number of digits.
%C A subsequence of A033308.
%H Harvey P. Dale, <a href="/A163117/b163117.txt">Table of n, a(n) for n = 1..2000</a>
%e a(1)=1 and a(2)=1 represent the two digits of 11.
%e a(7)=1 and a(8)=9 represent the two digits of 19.
%e a(43)=0 and a(44)=0 represent the two zeros of the prime 1009.
%t cd[n_]:=Module[{idn=IntegerDigits[n],len},len=IntegerLength[n]/2;Take[ idn,{len,len+1}]]; cd/@Select[Prime[Range[200]],EvenQ[ IntegerLength[ #]]&]//Flatten (* _Harvey P. Dale_, Jul 23 2018 *)
%Y Cf. A093339, A162908.
%K nonn,base,less
%O 1,4
%A _Juri-Stepan Gerasimov_, Jul 21 2009
%E a(8) corrected by _R. J. Mathar_, Jul 27 2009
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