OFFSET
1,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).
FORMULA
G.f.: x^2*(1+x+2*x^2+2*x^3+2*x^4) / ( (x^4+x^3+x^2+x+1)*(x-1)^2 ). - R. J. Mathar, Dec 05 2011
From Wesley Ivan Hurt, Aug 08 2016: (Start)
a(n) = a(n-1) + a(n-5) - a(n-6) for n > 6.
a(n) = a(n-5) + 8 for n > 5.
a(n) = (40*n - 55 - 2*(n mod 5) - 2*((n+1) mod 5) + 3*((n+2) mod 5) + 3*((n+3) mod 5) - 2*((n+4) mod 5))/25.
a(5*k) = 8*k-2, a(5*k-1) = 8*k-4, a(5*k-2) = 8*k-6, a(5*k-3) = 8*k-7, a(5*k-4) = 8*k-8. (End)
a(n) = (40*n-55+6*cos(2*Pi*(n-1)/5)+2*cos(2*Pi*n/5)+2*cos(4*Pi*n/5)-2*cos(2*Pi*(n+1)/5)-6*cos(Pi*(4*n+1)/5)+6*sin(Pi*(4*n+3)/10)+2*sin(Pi*(8*n+3)/10)-6*sin(Pi*(8*n+1)/10))/25. - Wesley Ivan Hurt, Oct 10 2018
MAPLE
A047412:=n->8*floor(n/5)+[(0, 1, 2, 4, 6)][(n mod 5)+1]: seq(A047412(n), n=0..100); # Wesley Ivan Hurt, Aug 08 2016
MATHEMATICA
Flatten[Table[8*n + {0, 1, 2, 4, 6}, {n, 0, 11}]] (* Alonso del Arte, Sep 21 2011 *)
Select[Range[0, 150], MemberQ[{0, 1, 2, 4, 6}, Mod[#, 8]] &] (* Vincenzo Librandi, Mar 01 2016 *)
LinearRecurrence[{1, 0, 0, 0, 1, -1}, {0, 1, 2, 4, 6, 8}, 100] (* Harvey P. Dale, Aug 06 2018 *)
PROG
(PARI) a(n)=n\5*8 + [0, 1, 2, 4, 6][n%5+1] \\ Charles R Greathouse IV, Oct 27 2015
(Magma) [n : n in [0..140] | n mod 8 in [0, 1, 2, 4, 6] ]; // Vincenzo Librandi, Mar 01 2016
(GAP) Filtered([0..105], n->n mod 8 = 0 or n mod 8 = 1 or n mod 8 = 2 or n mod 8 = 4 or n mod 8 = 6); # Muniru A Asiru, Oct 23 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved