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A088061
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a(1) = 11, a(n) = smallest prime obtained by starting with a(n-1) and prefixing it with one or more copies of (the decimal expansion of) n.
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2
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OFFSET
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1,1
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COMMENTS
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Next term has 657 digits and is too large to include. - David Wasserman, Jul 01 2005
a(9) has 1280 digits: 623 repeats of "9" + 634 repeats of "8" + 12 repeats of "7" + "65544433211". a(10) has 4990 digits: 1855 repeats of "10" + a(9). a(8), a(9), a(10) are verified by PARI ispseudoprime function. - Dmitry Petukhov, Oct 15 2017
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LINKS
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EXAMPLE
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a(3) = 33211 as 3211 is not a prime but 33211 is.
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PROG
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(PARI) x=0; n=-1; for(k=1, 9, z=n; while(1, n++; x=x+k*10^n; if(ispseudoprime(x), print(x); break))) \\ Dmitry Petukhov, Oct 15 2017
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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