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A108817
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Primes of the form n*10^x + n - 1, where 0 < n < 9, x = 0,1,2,3...
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OFFSET
| 1,1
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COMMENTS
| The next 2 terms for x <= 1000 are 4*10^419+3 and 4*10^449+3 both PARI proved primes. Except for the first 5 terms, the outer digits of these numbers are 4 and 3. This follows from the fact that all other combinations produce multiples of 2,3 or 5.
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EXAMPLE
| n=4,x=3. a(x,n) = 4*10^3+4-1 = 4003 prime.
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PROG
| (PARI) n10nm1(n) = { local(x, y, k); for(x=0, n, for(k=1, 8, y=10^x*k+k-1; if(isprime(y), print1(y", ")) ) ) }
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CROSSREFS
| Sequence in context: A179739 A093988 A175914 * A123677 A133954 A087325
Adjacent sequences: A108814 A108815 A108816 * A108818 A108819 A108820
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KEYWORD
| nonn
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AUTHOR
| Cino Hilliard (hillcino368(AT)gmail.com), Jul 11, 2005
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