A047484 Numbers that are congruent to {3, 5, 7} mod 8.
3, 5, 7, 11, 13, 15, 19, 21, 23, 27, 29, 31, 35, 37, 39, 43, 45, 47, 51, 53, 55, 59, 61, 63, 67, 69, 71, 75, 77, 79, 83, 85, 87, 91, 93, 95, 99, 101, 103, 107, 109, 111, 115, 117, 119, 123, 125, 127, 131, 133, 135, 139, 141, 143, 147, 149, 151, 155, 157, 159
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
- Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1).
Programs
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Magma
I:=[3, 5, 7, 11]; [n le 4 select I[n] else Self(n-1)+Self(n-3) -Self(n-4): n in [1..70]]; // Vincenzo Librandi, May 17 2012
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Maple
A047484:=n->(24*n-3-6*cos(2*n*Pi/3)+2*sqrt(3)*sin(2*n*Pi/3))/9: seq(A047484(n), n=1..100); # Wesley Ivan Hurt, Jun 10 2016
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Mathematica
Select[Range[0,300], MemberQ[{3,5,7}, Mod[#,8]]&] (* Vincenzo Librandi, May 17 2012 *)
Formula
G.f.: x*(3+2*x+2*x^2+x^3)/((1-x)^2*(1+x+x^2)). [Colin Barker, May 14 2012]
a(n) = a(n-1) + a(n-3) - a(n-4) for n>4. - Vincenzo Librandi, May 17 2012
From Wesley Ivan Hurt, Jun 10 2016: (Start)
a(n) = (24*n-3-6*cos(2*n*Pi/3)+2*sqrt(3)*sin(2*n*Pi/3))/9.
a(3k) = 8k-1, a(3k-1) = 8k-3, a(3k-2) = 8k-5. (End)
a(n) = 3*n - floor((n-1)/3) - ((n-1) mod 3). - Wesley Ivan Hurt, Sep 26 2017
a(n) = 2*(n + floor((n-1)/3)) + 1. - Wolfdieter Lang, Sep 11 2021