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Minimal nested palindromic primes with seed 4.
2

%I #8 Sep 29 2015 12:31:33

%S 4,11411,1114111,18111411181,741811141118147,1674181114111814761,

%T 90167418111411181476109,3901674181114111814761093,

%U 14390167418111411181476109341,9143901674181114111814761093419,75914390167418111411181476109341957

%N Minimal nested palindromic primes with seed 4.

%C Let s be a palindrome and put a(1) = s. Let a(2) be the least palindromic prime having s in the middle; for n > 2, let a(n) be the least palindromic prime have a(n-1) in the middle. Then (a(n)) is the sequence of minimal nested palindromic primes with seed s.

%H Clark Kimberling, <a href="/A261821/b261821.txt">Table of n, a(n) for n = 1..200</a>

%e As a triangle:

%e .........4

%e .......11411

%e ......1114111

%e ....18111411181

%e ..741811141118147

%e 1674181114111814761

%t s = {4}; Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s]], Reverse[#]] &[IntegerDigits[#]]]] &]; AppendTo[s, tmp], {15}]; s

%t (* _Peter J. C. Moses_, Sep 01 2015 *)

%Y Cf. A261881 (seed 0, with guide to related sequences).

%K nonn,easy,base

%O 1,1

%A _Clark Kimberling_, Sep 23 2015