A261820 Minimal nested palindromic primes with seed 111.

111, 1311131, 113111311, 91131113119, 9911311131199, 12991131113119921, 771299113111311992177, 1077129911311131199217701, 11107712991131113119921770111, 101110771299113111311992177011101, 107101110771299113111311992177011101701

Offset: 1

Author

Clark Kimberling, Sep 24 2015

Keywords

• nonn
• base
• easy

Comments

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 having a(n-1) in the middle. Then (a(n)) is the sequence of minimal nested palindromic primes with seed s.

Examples

			As a triangle:
        111
      1311131
     113111311
    91131113119
   9911311131199
  12991131113119921
771299113111311992177
		

Links

• Clark Kimberling, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A261881.

Programs

Mathematica

s0 = "111"; s = {ToExpression[s0]};Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s], 10, Max[StringLength[s0],Length[IntegerDigits[Last[s]]]]], Reverse[#]]&[IntegerDigits[#]]]] &]; AppendTo[s, tmp], {10}]; s0 <> ", " <> StringTake[ToString[Rest[s]], {2, -2}]
(* Peter J. C. Moses, Sep 23 2015 *)