OFFSET
0,3
COMMENTS
LINKS
FORMULA
G.f.: 1/((1-x)*(1-x^2)*(1-x^5)*(1-x^10)*(1-x^20)*(1-x^50)*(1-x^100)).
EXAMPLE
a(5) is 4 because 1+1+1+1+1 = 2+1+1+1 = 2+2+1 = 5.
MATHEMATICA
f[n_] := Length@ IntegerPartitions[n, All, {1, 2, 5, 10, 20, 50, 100}]; Array[f, 75, 0] (* or *)
CoefficientList[ Series[1/((1 - x) (1 - x^2) (1 - x^5) (1 - x^10) (1 - x^20) (1 - x^50) (1 - x^100)), {x, 0, 75}], x] (* or *)
Table[ Length@ FrobeniusSolve[{1, 2, 5, 10, 20, 50, 100}, n]], {n, 0, 75}] (* much slower *)
PROG
(PARI) coins(v[..])=my(x='x); prod(i=1, #v, 1/(1-x^v[i]))
Vec(coins(1, 2, 5, 10, 20, 50, 100)+O(x^99)) \\ Charles R Greathouse IV, Jan 24 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Nov 25 2020
STATUS
approved