OFFSET
0,5
COMMENTS
Number of partitions of n into parts 1, 4, 5 and 9. - Ilya Gutkovskiy, May 17 2017
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,0,-1,0,0,0,0,0,0,-1,0,1, 0,0,1,-1).
FORMULA
a(n) = floor((2*n^3 + 57*n^2 + 480*n + 72*(-1)^n + 2208)/2160 + (1/5)*([(n mod 5) in {0,4}] - [(n mod 5) in {1,2}])). - Hoang Xuan Thanh, Aug 04 2025
MATHEMATICA
CoefficientList[Series[1/((1 - x)*(1 - x^4)*(1 - x^5)*(1 - x^9)), {x, 0, 50}], x] (* G. C. Greubel, May 17 2017 *)
LinearRecurrence[{1, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, -1, 0, 1, 0, 0, 1, -1}, {1, 1, 1, 1, 2, 3, 3, 3, 4, 6, 7, 7, 8, 10, 12, 13, 14, 16, 19}, 60] (* Harvey P. Dale, Apr 21 2019 *)
PROG
(PARI) x='x+O('x^50); Vec(1/((1 - x)*(1 - x^4)*(1 - x^5)*(1 - x^9))) \\ G. C. Greubel, May 17 2017
(PARI) a(n) = floor((2*n^3 + 57*n^2 + 480*n + 72*(-1)^n + 2208)/2160 + (1/5)*[1, -1, -1, 0, 1][n%5+1]) \\ Hoang Xuan Thanh, Aug 04 2025
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved
