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Search: id:A065821
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| A065821 |
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a(n) is the first prime ending in exactly n 1's. |
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+0
9
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| 31, 11, 2111, 101111, 311111, 29111111, 61111111, 1711111111, 14111111111, 31111111111, 311111111111, 2111111111111, 31111111111111, 3511111111111111, 5111111111111111, 101111111111111111, 3511111111111111111
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,100
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EXAMPLE
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a(4) = 101111 because 1111=11*101, 21111=3*31*227, 31111=53*587, 41111=7^2*829, 51111=3^4*631, 61111=23*2657, 71111=17*47*89, 81111=3*19*1423, 91111=179*509 so 101111 is the first prime ending in four 1's.
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PROGRAM
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(PARI) { b=0; f=1; for (n=1, 100, b=10*b + 1; f*=10; k=0; while (!isprime(b + k*f), if (k%10, k++, k+=2)); write("b065821.txt", n, " ", b + k*f) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Nov 01 2009]
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CROSSREFS
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Cf. A037055, A065584, A065580, A065581, A065582.
Sequence in context: A029821 A040935 A145584 this_sequence A040934 A107114 A077397
Adjacent sequences: A065818 A065819 A065820 this_sequence A065822 A065823 A065824
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KEYWORD
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base,nonn,new
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AUTHOR
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Jonathan Ayres (jonathan.ayres(AT)btinternet.com), Nov 23 2001
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 04 2003
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