|
|
A333815
|
|
G.f.: Sum_{k>=1} x^(k*(3*k - 1)/2) / (1 - x^(3*k)).
|
|
5
|
|
|
1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 2, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 2, 2, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 2, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 2, 1, 0, 1, 0, 0, 1, 2, 1, 1, 0, 1, 3, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 2, 1, 1, 1, 0, 1, 1, 1, 0, 2, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,22
|
|
COMMENTS
|
Number of ways to write n as the difference of two pentagonal numbers.
|
|
LINKS
|
|
|
FORMULA
|
G.f.: Sum_{i>=0} Sum_{j>=i} Product_{k=i..j} x^(3*k + 1).
|
|
MATHEMATICA
|
nmax = 92; CoefficientList[Series[Sum[x^(k (3 k - 1)/2)/(1 - x^(3 k)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|