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A261820 Minimal nested palindromic primes with seed 111. 2
111, 1311131, 113111311, 91131113119, 9911311131199, 12991131113119921, 771299113111311992177, 1077129911311131199217701, 11107712991131113119921770111, 101110771299113111311992177011101, 107101110771299113111311992177011101701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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.

LINKS

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

EXAMPLE

As a triangle:

        111

      1311131

     113111311

    91131113119

   9911311131199

  12991131113119921

771299113111311992177

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 *)

CROSSREFS

Cf. A261881.

Sequence in context: A262647 A262631 A259747 * A262661 A156407 A292155

Adjacent sequences:  A261817 A261818 A261819 * A261821 A261822 A261823

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling, Sep 24 2015

STATUS

approved

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Last modified August 2 01:19 EDT 2021. Contains 346408 sequences. (Running on oeis4.)