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%I #13 Dec 28 2019 07:47:58
%S 11,13,311,313,131111,131113,313331,313333,1131131,1131133,3331331,
%T 3331333,3333131,3333133,3333311,3333313,111113111,111113113,
%U 113331311,113331313,331313111,331313113,331331111,331331113,333331331,333331333
%N Twin prime pairs using digits 1 and 3 only.
%C Both the members of the twin prime pairs are included.
%H Amiram Eldar, <a href="/A111070/b111070.txt">Table of n, a(n) for n = 1..10000</a>
%F a(2k) = a(2k-1) + 2.
%t s = Select[Flatten @ Table[FromDigits /@ Tuples[{1, 3}, k], {k, 1, 9}], And @@ PrimeQ[10 # + {1, 3}] &]; Flatten @ Transpose @ {10 s + 1, 10 s + 3} (* _Amiram Eldar_, Dec 28 2019 *)
%Y Cf. A001097, A001359, A006512.
%K base,nonn
%O 1,1
%A _Amarnath Murthy_, Jan 02 2006
%E Corrected and extended by _Farideh Firoozbakht_, Jan 05 2006
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