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A065437 Smallest base relative to which the n-th prime is palindromic. 1
3, 2, 2, 2, 10, 3, 2, 18, 3, 4, 2, 6, 5, 6, 46, 52, 4, 6, 5, 7, 2, 78, 5, 8, 8, 10, 102, 2, 5, 8, 2, 10, 136, 138, 148, 3, 7, 162, 166, 3, 178, 10, 6, 12, 6, 11, 8, 222, 8, 12, 3, 14, 12, 8, 2, 262, 268, 7, 11, 14, 282, 292, 7, 310, 2, 316, 15, 9, 346, 8, 10, 358, 366, 4, 13, 10, 388 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subset of A016026 for primes only.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Palindromic Primes

EXAMPLE

71 is the 20th prime and can be written as 131 in base 7, hence a(20)=7.

MATHEMATICA

PrimeMinBase[ n_ ] := NestWhile[ # + 1 &, 2, IntegerDigits[ Prime[ n ], # ] != Reverse[ IntegerDigits[ Prime[ n ], # ] ] & ]

sbr[n_]:=Module[{k=2}, While[IntegerDigits[n, k]!=Reverse[ IntegerDigits[ n, k]], k++]; k]; Table[sbr[n], {n, Prime[Range[80]]}] (* Harvey P. Dale, Jun 07 2016 *)

CROSSREFS

Cf. A016026.

Sequence in context: A090207 A202538 A239736 * A097721 A073756 A328829

Adjacent sequences:  A065434 A065435 A065436 * A065438 A065439 A065440

KEYWORD

base,easy,nonn

AUTHOR

Peter Bertok (peter(AT)bertok.com), Nov 23 2001

STATUS

approved

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Last modified December 13 01:23 EST 2019. Contains 329963 sequences. (Running on oeis4.)