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A047389
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Numbers that are congruent to {3, 5} mod 7.
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0
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3, 5, 10, 12, 17, 19, 24, 26, 31, 33, 38, 40, 45, 47, 52, 54, 59, 61, 66, 68, 73, 75, 80, 82, 87, 89, 94, 96, 101, 103, 108, 110, 115, 117, 122, 124, 129, 131, 136, 138, 143, 145, 150, 152, 157, 159, 164, 166, 171
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Primitive roots of 7. The first differences are periodic: 2,5,2,5,2,5.... - Paolo P. Lava (paoloplava(AT)gmail.com), Feb 29 2008
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (1,1,-1).
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FORMULA
| a(n)=-4+(1/2)*Sum_{k=0..n}{7-3*(-1)^n}, with n>=1 - Paolo P. Lava (paoloplava(AT)gmail.com), Feb 29 2008
a(n)=7*n-a(n-1)-6, n>1. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 05 2010]
Contribution from Bruno Berselli (berselli.bruno(AT)yahoo.it), Sep 08 2010: (Start)
G.f.: x*(3+2*x+2*x^2)/((1+x)*(1-x)^2).
a(n)-a(n-1)-a(n-2)+a(n-3)=0 for n>3.
a(n)=(14*n-5-3*(-1)^n)/4. (End)
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MAPLE
| P:=proc(n, m) local a, i, ok; for i from 1 by 1 to n do if (i^(m-1) mod m)=1 then a:=1; ok:=1; while a<m-1 do if (i^a mod m)=1 then ok:=0; fi; a:=a+1; od; if ok=1 then print(i); fi; fi; od; end: P(100, 7); - Paolo P. Lava (paoloplava(AT)gmail.com), Feb 29 2008
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CROSSREFS
| Sequence in context: A067230 A075741 A119133 * A093661 A080561 A007557
Adjacent sequences: A047386 A047387 A047388 * A047390 A047391 A047392
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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