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A376103 a(1) = 5; for n > 1, a(n) is the smallest palindromic prime containing exactly 2 more digits on each end than a(n-1), with a(n-1) as the central substring.

%I A376103 #6 Oct 02 2024 14:40:34
%S A376103 5,10501,111050111,1211105011121,39121110501112193,
%T A376103 393912111050111219393,7239391211105011121939327,
%U A376103 79723939121110501112193932797,157972393912111050111219393279751,7415797239391211105011121939327975147
%N A376103 a(1) = 5; for n > 1, a(n) is the smallest palindromic prime containing exactly 2 more digits on each end than a(n-1), with a(n-1) as the central substring.
%C A376103 This is a finite sequence since at a(10) there is no way to add 2 more digits and reach a palindromic prime.
%e A376103 As a triangle:
%e A376103           5
%e A376103         10501
%e A376103       111050111
%e A376103     1211105011121
%e A376103   39121110501112193
%Y A376103 Cf. A047076, A053600, A375690, A082563.
%K A376103 nonn,base,fini,full
%O A376103 1,1
%A A376103 _Shyam Sunder Gupta_, Sep 10 2024