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+x^2+2*x^3+2*x^4)/ ( (x^4+x^3+x^2+x+1)*(x-1)^2 ). - R. J. Mathar, Dec 04 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) + 7 for n > 5.
a(n) = (35*n - 50 - 3*(n mod 5) + 2*((n+1) mod 5) + 2*((n+2) mod 5) + 2*((n+3) mod 5) - 3*((n+4) mod 5))/25.
a(5*k) = 7*k-2, a(5*k-1) = 7*k-4, a(5*k-2) = 7*k-5, a(5*k-3) = 7*k-6, a(5*k-4) = 7*k-7. (End)
MAPLE
A047373:=n->7*floor(n/5)+[(0, 1, 2, 3, 5)][(n mod 5)+1]: seq(A047373(n), n=0..100); # Wesley Ivan Hurt, Aug 08 2016
MATHEMATICA
Select[Range[0, 100], MemberQ[{0, 1, 2, 3, 5}, Mod[#, 7]] &] (* Wesley Ivan Hurt, Aug 08 2016 *)
LinearRecurrence[{1, 0, 0, 0, 1, -1}, {0, 1, 2, 3, 5, 7}, 100] (* Vincenzo Librandi, Aug 08 2016 *)
PROG
(Magma) [n : n in [0..150] | n mod 7 in [0, 1, 2, 3, 5]]; // Wesley Ivan Hurt, Aug 08 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved