OFFSET
1,1
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).
FORMULA
G.f.: x*(17+2*x+12*x^2+2*x^3+67*x^4)/(1-x-x^4+x^5). - Colin Barker, Jan 23 2012
a(n) = -75/2 - (23*(-1)^n)/2 - (9-9*i)*(-i)^n - (9+9*i)*i^n + 25*n where i=sqrt(-1). - Colin Barker, Oct 16 2015
MATHEMATICA
Select[Range[1300], MemberQ[{17, 19, 31, 33}, Mod[#, 100]]&] (* or *) LinearRecurrence[{1, 0, 0, 1, -1}, {17, 19, 31, 33, 117}, 50] (* Harvey P. Dale, Dec 17 2014 *)
PROG
(Haskell)
import Data.List (findIndices)
a045803 n = a045803_list !! (n-1)
a045803_list = findIndices (`elem` [17, 19, 31, 33]) $ cycle [0..99]
-- Reinhard Zumkeller, Jan 23 2012
(PARI) a(n) = -75/2 - (23*(-1)^n)/2 - (9-9*I)*(-I)^n - (9+9*I)*I^n + 25*n \\ Colin Barker, Oct 16 2015
(PARI) Vec(x*(17+2*x+12*x^2+2*x^3+67*x^4)/(1-x-x^4+x^5) + O(x^100)) \\ Colin Barker, Oct 16 2015
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
More terms from Erich Friedman
STATUS
approved