OFFSET
0,2
COMMENTS
Numbers n such that n/2 is a square and n/3 is a cube.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).
FORMULA
a(n) = 648*n^6 = 648*A001014(n).
G.f.: -648*x*(x+1)*(x^4+56*x^3+246*x^2+56*x+1) / (x-1)^7.
EXAMPLE
41472 is a member since 41472/2 = 20736 = 144^2 and 41472/3 = 13824 = 24^3.
MATHEMATICA
Table[648*n^6, {n, 0, 23}] (* Zak Seidov, Jun 11 2015 *)
LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {0, 648, 41472, 472392, 2654208, 10125000, 30233088}, 30] (* Harvey P. Dale, Mar 31 2016 *)
PROG
(PARI) a(n)=648*n^6 \\ Charles R Greathouse IV, Jun 11 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jayanta Basu, Apr 23 2013
STATUS
approved