A065437 Smallest base relative to which the n-th prime is palindromic.

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

Offset: 1

Author

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

Keywords

• base
• easy
• nonn

Comments

Subset of A016026 for primes only.

Examples

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

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000
• Eric Weisstein's World of Mathematics, Palindromic Primes

Crossrefs

Cf. A016026.

Programs

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 *)