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A262499 Minimal nested palindromic primes with seed 111111111. 2
111111111, 1311111111131, 31131111111113113, 3311311111111131133, 333113111111111311333, 3033311311111111131133303, 1323033311311111111131133303231, 313230333113111111111311333032313, 9531323033311311111111131133303231359 (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
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
KEYWORD
nonn,base,easy
AUTHOR
Clark Kimberling, Sep 24 2015
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)