OFFSET
1,2
LINKS
E. Angelini, k-chunks sum and division by k, post to the SeqFan list, Mar 22 2013
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,2,0,0,0,0,-1).
FORMULA
a(n) = 2 a(n-5) - a(n-10).
G.f.: x*(1 + 2*x + 3*x^2 + 4*x^3 + 5*x^4 + 4*x^5 + 3*x^6 + 2*x^7 + x^8 + 5*x^9)/((1 - x)*(1 + x + x^2 + x^3 + x^4))^2.
a(n)=n unless n=0 (mod 5) in which case a(n)=2n-5.
MATHEMATICA
LinearRecurrence[{0, 0, 0, 0, 2, 0, 0, 0, 0, -1}, {1, 2, 3, 4, 5, 6, 7, 8, 9, 15}, 90] (* Harvey P. Dale, Jul 31 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric Angelini and M. F. Hasler, Mar 23 2013
STATUS
approved