OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1).
FORMULA
a(n) = 1 + floor((3/4)*n^2).
G.f.: x*(1+2*x-x^2+x^3) / ( (1+x)*(1-x)^3 ). - R. J. Mathar, Aug 25 2011
a(n) = 1 + 3*A002620(n). - R. J. Mathar, Aug 25 2011
MATHEMATICA
c[k_]:=1+Floor[(3/4)k^2];
Table[c[k], {k, 1, 90}]
PROG
(PARI) a(n)=3*n^2\4+1 \\ Charles R Greathouse IV, Oct 16 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Aug 14 2011
STATUS
approved