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A047354
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Numbers that are congruent to {0, 1, 2} mod 7.
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0
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0, 1, 2, 7, 8, 9, 14, 15, 16, 21, 22, 23, 28, 29, 30, 35, 36, 37, 42, 43, 44, 49, 50, 51, 56, 57, 58, 63, 64, 65, 70, 71, 72, 77, 78, 79, 84, 85, 86, 91, 92, 93, 98, 99, 100, 105, 106, 107, 112, 113, 114, 119, 120
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| a(n)= 7*floor(n/3) +(n mod 3), with offset 0...a(0)=0 [From Gary Detlefs (gdetlefs(AT)aol.com), Mar 09 2010]
a(n)= +a(n-1) +a(n-3) -a(n-4). G.f.: x^2*(1+x+5*x^2)/((1+x+x^2) * (x-1)^2). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 29 2010]
a(n+1)=Sum_k>=0 {A030341(n,k)*b(k)} with b(0)=1 and b(k)=7*3^(k-1) for k>0. - From DELEHAM Philippe, Oct 24 2011.
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MAPLE
| seq(7*floor(n/3) +(n mod 3), n=0..60); [From Gary Detlefs (gdetlefs(AT)aol.com), Mar 09 2010]
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MATHEMATICA
| Flatten[{#, #+1, #+2}&/@(7Range[0, 20])] (* From Harvey P. Dale, Mar 5 2011 *)
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CROSSREFS
| Sequence in context: A064517 A167457 A179772 * A037455 A020675 A045980
Adjacent sequences: A047351 A047352 A047353 * A047355 A047356 A047357
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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