A376103 - OEIS

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 #6 Oct 02 2024 14:40:34

%S 5,10501,111050111,1211105011121,39121110501112193,

%T 393912111050111219393,7239391211105011121939327,

%U 79723939121110501112193932797,157972393912111050111219393279751,7415797239391211105011121939327975147

%N 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 This is a finite sequence since at a(10) there is no way to add 2 more digits and reach a palindromic prime.

%e As a triangle:

%e 5

%e 10501

%e 111050111

%e 1211105011121

%e 39121110501112193

%Y Cf. A047076, A053600, A375690, A082563.

%K nonn,base,fini,full

%O 1,1

%A _Shyam Sunder Gupta_, Sep 10 2024