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a(1) = 7 and then the smallest prime that is obtained by placing digits on both sides of the previous term. Or smallest prime that encompasses a(n-1).
7

%I #7 Dec 05 2013 19:55:39

%S 7,173,11731,2117317,421173173,34211731733,1342117317337,

%T 813421173173377,28134211731733771,4281342117317337713,

%U 142813421173173377131,21428134211731733771317,2214281342117317337713171,2221428134211731733771317113,922214281342117317337713171139

%N a(1) = 7 and then the smallest prime that is obtained by placing digits on both sides of the previous term. Or smallest prime that encompasses a(n-1).

%Y Cf. A075595, A075596, A075597, A075598, A075600, A075601, A075602.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Sep 28 2002

%E More terms from _Sascha Kurz_, Jan 20 2003

%E Further terms from _Ray G. Opao_, Nov 26 2004