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A057186
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Numbers n such that (20^n+1)/21 is a prime.
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1
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OFFSET
| 1,1
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COMMENTS
| (20^1163+1)/21, a 1512-digit number, has been certified prime with Primo. - Rick L. Shepherd (rshepherd2(AT)hotmail.com), May 17 2002
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LINKS
| H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
Paul Bourdelais,A Generalized Repunit Conjecture [From Paul Bourdelais (pbourdelais(AT)radiantblue.com), Apr 06 2010]
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PROG
| (Other) PFGW v3.3.1 [From Paul Bourdelais (pbourdelais(AT)radiantblue.com), Apr 06 2010]
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CROSSREFS
| Sequence in context: A015056 A015973 A136578 * A106939 A142114 A200986
Adjacent sequences: A057183 A057184 A057185 * A057187 A057188 A057189
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Sep 15 2000
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EXTENSIONS
| a(8)=140053 is a probable prime discovered by Paul Bourdelais (pbourdelais(AT)radiantblue.com), Apr 06 2010
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