OFFSET
0,2
COMMENTS
When the elliptic term: j=g2^3/(g2^3-27*g3^2) is singular and g2 and g3 are both integers.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,4,0,-6,0,4,0,-1).
FORMULA
a(n) = If 3*n^(2/3) is an integer then {n,3*n^(2/3)}
a(n) = (n^3+6*n^2+12*n+8)/8 for n even. a(n) = (3*n^2+6*n+3)/4 for n odd. G.f.: -(3*x^5-x^4-4*x^2-3*x-1) / ((x-1)^4*(x+1)^4). - Colin Barker, Mar 15 2013
MATHEMATICA
a = Flatten[Table[If[IntegerQ[3*n^(2/3)] == True, {n, 3*n^(2/3)}, {}], {n, 1, 5000}]]
CROSSREFS
KEYWORD
nonn,uned,easy
AUTHOR
Roger L. Bagula, Feb 18 2006
STATUS
approved