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A047216
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Numbers that are congruent to {1, 2} mod 5.
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20
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1, 2, 6, 7, 11, 12, 16, 17, 21, 22, 26, 27, 31, 32, 36, 37, 41, 42, 46, 47, 51, 52, 56, 57, 61, 62, 66, 67, 71, 72, 76, 77, 81, 82, 86, 87, 91, 92, 96, 97, 101, 102, 106, 107, 111, 112, 116, 117, 121, 122, 126, 127, 131, 132, 136, 137, 141, 142, 146, 147
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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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)=5*n-a(n-1)-7 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 05 2010]
G.f. x*(1+x+3*x^2) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Oct 08 2011
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MATHEMATICA
| Select[Range[0, 200], MemberQ[{1, 2}, Mod[#, 5]] &] (* From Vladimir Joseph Stephan Orlovsky, Feb 12 2012 *)
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PROG
| (PARI) a(n)=(n-1)\2*5+2-n%2 \\ Charles R Greathouse IV, Dec 22 2011
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CROSSREFS
| Cf. A047209, A047211, A047212
Sequence in context: A061943 A029507 A047552 * A039568 A032926 A088227
Adjacent sequences: A047213 A047214 A047215 * A047217 A047218 A047219
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KEYWORD
| nonn,easy,changed
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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