OFFSET
0,3
COMMENTS
a(n) is the smallest number whose sum of odd decimal digits is n.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,10,-10).
FORMULA
G.f.: x*(1 + 2*x*(5 - 4*x)*(1 + x^2)*(1 + x^4))/((1 - x)*(1 - 10*x^9)).
a(n) = a(n-1) + 10*a(n-9) - 10*a(n-10).
MATHEMATICA
CoefficientList[Series[x (1 + 2 x (5 - 4 x) (1 + x^2) (1 + x^4))/((1 - x) (1 - 10 x^9)), {x, 0, 48}], x]
LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 10, -10}, {0, 1, 11, 3, 13, 5, 15, 7, 17, 9}, 49]
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Ilya Gutkovskiy, Aug 15 2018
STATUS
approved