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 A028989 Smallest palindromic prime with 2n-1 digits. 4
 2, 101, 10301, 1003001, 100030001, 10000500001, 1000008000001, 100000323000001, 10000000500000001, 1000000008000000001, 100000000212000000001, 10000000000300000000001 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..500 P. De Geest, World!Of Palindromic Primes MATHEMATICA t={}; Do[p=NextPrime[10^(2*n)]; While[Reverse[x=IntegerDigits[p]]!=x, p=NextPrime[p]]; AppendTo[t, p], {n, 0, 6}]; t (* Jayanta Basu, Jun 05 2013 *) PROG (PARI) a(n)={ n--; my(N=100^n+1, aS=10^(n+3)+10^(n-3), bS=10^(n+2)+10^(n-2), cS=10^(n+1)+10^(n-1), dS=10^n); forstep(a=N, N+9*aS, aS, forstep(b=a, a+9*bS, bS, forstep(c=b, b+9*cS, cS, forstep(d=c, c+9*dS, dS, if(ispseudoprime(d), return(d)) )))); warning("could not find a("n")") }; \\ Charles R Greathouse IV, Feb 15 2011 CROSSREFS Odd-numbered terms of A056732. - Edward Catmur, May 01 2015 Sequence in context: A222449 A035325 A266457 * A113575 A173640 A111012 Adjacent sequences:  A028986 A028987 A028988 * A028990 A028991 A028992 KEYWORD nonn,base AUTHOR EXTENSIONS a(10) corrected by Farideh Firoozbakht, Oct 10 2005 STATUS approved

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Last modified January 25 01:33 EST 2020. Contains 331229 sequences. (Running on oeis4.)