OFFSET
1,2
LINKS
B. Berselli, Table of n, a(n) for n = 1..100000. [From Bruno Berselli, Sep 21 2010]
FORMULA
Integers of the form (k^4+1)*( (k-1)*(k+1)*(k^2+1) )^2/512.
a(n) = ((2*n-1)^4+1)*((n-1)*n*(n^2+(n-1)^2))^2/8 (for k=2n-1).
EXAMPLE
a(2) = 1025 is in the sequence because (3^12 - 3^8 - 3^4 + 1)/512 = 524800/512 = 1025.
MAPLE
for n from 1 by 2 to 60 do: x:= (n^12-n^8 -n^4+1)/512: printf(`%d, `, x):od: # incomplete program which also prints rationals, R. J. Mathar
MATHEMATICA
Select[Table[(k^12-k^8-k^4+1)/512, {k, 40}], IntegerQ] (* Harvey P. Dale, Jan 23 2011 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Lagneau, Aug 23 2010
EXTENSIONS
Comment converted to formula by R. J. Mathar, Aug 25 2010
Example corrected and general term of the sequence rewritten by Bruno Berselli, Sep 22 2010
STATUS
approved