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A047215
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Numbers that are congruent to {0, 2} mod 5.
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24
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0, 2, 5, 7, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, 77, 80, 82, 85, 87, 90, 92, 95, 97, 100, 102, 105, 107, 110, 112, 115, 117, 120, 122, 125, 127, 130, 132, 135, 137, 140, 142, 145, 147, 150, 152, 155, 157
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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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) = floor(5n/2).
G.f.: x(2+3x)/((1+x)(1-x)^2). a(n) = 5n/2 +((-1)^n-1)/4. a(n+1)-a(n)=A010693(n+1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 23 2008]
a(n)=5*n-a(n-1)-8 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 05 2010]
a(n+1)=Sum_k>=0 {A030308(n,k)*A084215(k+1)}. - From DELEHAM Philippe, Oct 17 2011.
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EXAMPLE
| For n=2, a(2)=5*2-0-8=2; n=3, a(3)=5*3-2-8=5; n=4, a(4)=5*4-5-8=7 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 05 2010]
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MATHEMATICA
| Table[Floor[5*n/2], {n, 0, 100}] (* or *) LinearRecurrence[{1, 1, -1}, {0, 2, 5}, 101] (* From Vladimir Joseph Stephan Orlovsky, Jan 28 2012 *)
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PROG
| (PARI) a(n)=5*n\2 \\ Charles R Greathouse IV, Oct 17 2011
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CROSSREFS
| Different from A038126.
Sequence in context: A022849 A075328 A038126 * A059536 A030193 A028250
Adjacent sequences: A047212 A047213 A047214 * A047216 A047217 A047218
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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