OFFSET
0,5
FORMULA
a(n) = Sum_{k=1..floor(n/4)} Sum_{j=k..floor((n-k)/3)} Sum_{i=j..floor((n-j-k)/2)} [k = 1] + [j = 1] + [i = 1] + [n-i-j-k = 1], where [ ] is the Iverson bracket.
MATHEMATICA
Table[Sum[Sum[Sum[KroneckerDelta[k, 1] + KroneckerDelta[j, 1] + KroneckerDelta[i, 1] + KroneckerDelta[n - i - j - k, 1], {i, j, Floor[(n - j - k)/2]}], {j, k, Floor[(n - k)/3]}], {k, Floor[n/4]}], {n, 0, 80}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jan 26 2021
STATUS
approved