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A262499 revision #7

A262499

Minimal nested palindromic primes with seed 111111111.

111111111, 1311111111131, 31131111111113113, 3311311111111131133, 333113111111111311333, 3033311311111111131133303, 1323033311311111111131133303231, 313230333113111111111311333032313, 9531323033311311111111131133303231359

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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:

111111111

1311111111131

31131111111113113

3311311111111131133

333113111111111311333

3033311311111111131133303

1323033311311111111131133303231

313230333113111111111311333032313

MATHEMATICA

s0 = "111111111"; 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: A172525 A038451 A202082 * A068538 A186552 A147581

Adjacent sequences: A262496 A262497 A262498 * A262500 A262501 A262502

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling, Sep 24 2015

STATUS

proposed