OFFSET
0,1
COMMENTS
Northwest corner values of Ulam spiral with 101 at center.
LINKS
FORMULA
a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). G.f.: -(107-220*x+121*x^2)/(x-1)^3. - R. J. Mathar, Jul 24 2009
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {107, 101, 103}, 50] (* Harvey P. Dale, Jun 05 2012 *)
PROG
(PARI) a(n)=4*n^2-10*n+107 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Milton L. Brown (miltbrown(AT)earthlink.net), Jun 05 2009, Jul 21 2009
STATUS
approved