OFFSET
0,3
COMMENTS
a(n) is also the number of partitions of n with less than three 1's. - Geoffrey Critzer, Jun 20 2014
FORMULA
G.f.: (1-x^3) Product_{m>0} 1/(1-x^m).
a(n) ~ Pi * exp(sqrt(2*n/3)*Pi) / (4*sqrt(2)*n^(3/2)) * (1 - (3*sqrt(3/2)/Pi + Pi/(24*sqrt(6)) + 3*Pi/(2*sqrt(6)))/sqrt(n) + (37/8 + 9/(2*Pi^2) + 1801*Pi^2/6912)/n). - Vaclav Kotesovec, Nov 04 2016
MATHEMATICA
nn=49; CoefficientList[Series[(1-x^3)Product[1/(1-x^i), {i, 1, nn}], {x, 0, nn}], x] (* Geoffrey Critzer, Jun 20 2014 *)
PROG
(PARI) a(n)=if(n<0, 0, polcoeff((1-x^3)/eta(x+x*O(x^n)), n))
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved