OFFSET
1,1
LINKS
Jerry Polfer, Table of n, a(n) for n = 1..500
Project Euler, Problem 1: Multiples of 3 and 5
Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000).
FORMULA
G.f.: -x*(23-235*x+1400*x^2)/((x-1)*(100*x-1)*(10*x-1)). - Alois P. Heinz, Jan 30 2017
a(n) = (7/30)*100^n - (1/6)*10^n + 4/3. - Robert Israel, Jan 31 2017
EXAMPLE
For n = 1, a(1) = 3 + 5 + 6 + 9 = 23.
PROG
(PARI) Vec(-x*(23-235*x+1400*x^2)/((x-1)*(100*x-1)*(10*x-1)) + O(x^15)) \\ Felix Fröhlich, Jan 30 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jerry Polfer, Jan 29 2017
STATUS
approved