OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,-1,1,-2,1).
FORMULA
a(n) = n - 1 + ceiling((2/3)n^2).
MATHEMATICA
a=3/2; b=0;
Table[n+Floor[(a*n+b)^(1/2)], {n, 100}]
Table[n-1+Ceiling[(n*n-b)/a], {n, 80}]
LinearRecurrence[{2, -1, 1, -2, 1}, {1, 4, 8, 14, 21}, 60] (* Harvey P. Dale, Apr 12 2020 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jan 07 2011
STATUS
approved