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 A117785 Total number of palindromic primes in base 8 below 8^n. 0
 4, 4, 17, 17, 64, 64, 375, 375, 2319, 2319, 15130, 15130, 99554, 99554, 675166, 675166, 4753617, 4753617, 33752394, 33752394, 239605153, 239605153 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Every palindrome with an even number of digits is divisible by 11 (in base 8) and therefore is composite (not prime). Hence there is no palindromic prime with an even number of digits. LINKS Eric Weisstein: Palindromic Prime. MAPLE revdigs:= proc(n) local L, i;   L:= convert(n, base, 8);   add(L[-i]*8^(i-1), i=1..nops(L)) end proc: f:= proc(d) local x, y;      nops(select(isprime, [seq(seq(x*8^(d+1)+y*8^d+revdigs(x), y=0..7), x=8^(d-1)..8^d-1)])); end proc: T:= ListTools:-PartialSums([4, op(map(f, [\$1..6]))]): map(t -> (t, t), T); # Robert Israel, Aug 01 2019 CROSSREFS Cf. A029976, A006341. Partial sums of A117786. Sequence in context: A191972 A101407 A294245 * A117787 A113727 A214141 Adjacent sequences:  A117782 A117783 A117784 * A117786 A117787 A117788 KEYWORD nonn,base,more AUTHOR Martin Renner, Apr 15 2006 EXTENSIONS a(9)-a(22) from Robert Israel, Aug 01 2019, using data from A117786. STATUS approved

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Last modified February 26 09:44 EST 2020. Contains 332277 sequences. (Running on oeis4.)