OFFSET
0,2
COMMENTS
Related to the primitive Pythagorean triple [21, 20, 29].
LINKS
FORMULA
a(n) = (41*n^2 + 41*n)/2 = 41*n*(n+1)/2 = 41*A000217(n).
G.f.: -41*x / (x-1)^3 . - R. J. Mathar, Oct 04 2014
MATHEMATICA
41*Accumulate[Range[0, 40]] (* or *) LinearRecurrence[{3, -3, 1}, {0, 41, 123}, 40] (* Harvey P. Dale, Nov 20 2015 *)
PROG
(PARI) a(n)=41*n*(n+1)/2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Omar E. Pol, Sep 12 2011
STATUS
approved