OFFSET
0,3
COMMENTS
Number of ways of making change for 50n Colombian pesos using coins of 50, 100, 200, 500 and 1000 pesos.
Number of partitions of n into parts 1,2,4,10 and 20.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1, 1, -1, 1, -1, -1, 1, 0, 0, 1, -1, -1, 1, -1, 1, 1, -1, 0, 0, 1, -1, -1, 1, -1, 1, 1, -1, 0, 0, -1, 1, 1, -1, 1, -1, -1, 1).
FORMULA
G.f.: 1/((1 - x) (1 - x^2) (1 - x^4) (1 - x^10) (1 - x^20)).
a(n) = A000064(floor(n/2)).
a(n) ~ n^4/38400.
EXAMPLE
a(5)=4 counts the ways of making change for 5 cents, these are (1,1,1,1,1), (1,1,1,2), (1,2,2), (1,4).
MATHEMATICA
A[x_]:=1/((1 - x) (1 - x^2) (1 - x^4) (1 - x^10) (1 - x^20));
a[n_]:=SeriesCoefficient[A[x], {x, 0, n}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Daniel Checa, Nov 03 2022
STATUS
approved