A056732 Smallest palindromic prime using n digits, or 0 if no such number exists.

2, 11, 101, 0, 10301, 0, 1003001, 0, 100030001, 0, 10000500001, 0, 1000008000001, 0, 100000323000001, 0, 10000000500000001, 0, 1000000008000000001, 0, 100000000212000000001, 0, 10000000000300000000001, 0, 1000000000016100000000001, 0

Offset: 1

Author

Robert G. Wilson v, Aug 11 2000

Keywords

• nonn
• base

Crossrefs

Odd-numbered terms form A028989. - Edward Catmur, May 01 2015

Programs

Mathematica

Do[ k = 10^n; While[ ! PrimeQ[ k*10^n + FromDigits[ Take[ Reverse[ RealDigits[ k ][ [ 1 ] ] ], {2, -1} ] ] ], k++ ]; Print[ k*10^n + FromDigits[ Take[ Reverse[ RealDigits[ k ][ [ 1 ] ] ], {2, -1} ] ] ]; If[ n == 0, Print[ 11 ], Print[ 0 ] ], {n, 0, 12} ]

Formula

a(2*n) = 0 for n >= 2 (palindromes of even length are divisible by 11). - Joerg Arndt, May 01 2022

Extensions

a(25)-a(26) from Michael S. Branicky, Feb 12 2021

Name corrected by Joerg Arndt, May 01 2022