OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
FORMULA
From G. C. Greubel, Jul 17 2022: (Start)
a(n) = Sum_{j=0..n-1} (2*j+1)*A023533(n-j).
T(n, k) = (2*k+1)*n + 6*binomial(n+2, 4), for 0 <= k <= n*(n+3)/2 and n >= 1 (as an irregular triangle). (End)
MATHEMATICA
Table[(2*k+1)*n + 6*Binomial[n+2, 4], {n, 7}, {k, 0, n*(n+3)/2}]//Flatten (* G. C. Greubel, Jul 17 2022 *)
PROG
(Magma)
A023533:= func< n | Binomial(Floor((6*n-1)^(1/3)) +2, 3) ne n select 0 else 1 >;
[(&+[(2*k+1)*A023533(n-k): k in [0..n-1]]): n in [1..80]]; // G. C. Greubel, Jul 17 2022
(SageMath)
def A023660(n, k): return (2*k+1)*n + 6*binomial(n+2, 4)
flatten([[A023660(n, k) for k in (0..n*(n+3)/2)] for n in (1..7)]) # G. C. Greubel, Jul 17 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved