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A056732 Smallest palindromic prime using n digits, or 0 if no such number exists. 2

%I #21 May 01 2022 08:39:30

%S 2,11,101,0,10301,0,1003001,0,100030001,0,10000500001,0,1000008000001,

%T 0,100000323000001,0,10000000500000001,0,1000000008000000001,0,

%U 100000000212000000001,0,10000000000300000000001,0,1000000000016100000000001,0

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

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

%t 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} ]

%Y Odd-numbered terms form A028989. - _Edward Catmur_, May 01 2015

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Aug 11 2000

%E a(25)-a(26) from _Michael S. Branicky_, Feb 12 2021

%E Name corrected by _Joerg Arndt_, May 01 2022

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Last modified July 4 23:47 EDT 2024. Contains 374017 sequences. (Running on oeis4.)