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A088281
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a(1) = 11; for n > 1, palindromic primes in which a single digit is sandwiched between strings of '1's.
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7
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11, 101, 131, 151, 181, 191, 11311, 11411, 1114111, 1117111, 111181111, 111191111, 1111118111111, 111111151111111, 111111181111111, 111111111161111111111, 11111111111111611111111111111, 111111111111111111131111111111111111111, 11111111111111111111111111911111111111111111111111111
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OFFSET
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0,1
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COMMENTS
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LINKS
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PROG
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(PARI) print1(11); for(L=1, 19, for(d=0, 9, d!=1 && ispseudoprime(p=10^(2*L+1)\9+(d-1)*10^L) && print1(", "p))) \\ M. F. Hasler, Feb 07 2020
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CROSSREFS
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Cf. A105992 (near-repunit primes), A065074 (which contain the digit 0), A034093 (number of primes by changing one 1 to 0), A065083 (least k for which that = n).
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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