OFFSET
0,1
COMMENTS
Derivation is similar to that of A126665, which see for further information.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
Michael M. Ross, Natural Numbers.
Robert Sacks, Number Spiral: Method of Common Differences.
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
From Harvey P. Dale, Oct 19 2011: (Start)
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3), a(0)=23, a(1)=31, a(2)=37.
G.f.: ((38 - 13*x)*x - 23)/(x-1)^3. (End)
E.g.f.: exp(x)*(23 + 8*x - x^2). - Elmo R. Oliveira, Nov 02 2024
EXAMPLE
For n=8, -1*8^2 + 9*8 + 23 = 31.
MAPLE
MATHEMATICA
Table[-n^2+9n+23, {n, 0, 60}] (* or *) LinearRecurrence[{3, -3, 1}, {23, 31, 37}, 60] (* Harvey P. Dale, Oct 19 2011 *)
PROG
(PARI) a(n)=-n^2+9*n+23 \\ Charles R Greathouse IV, Oct 07 2015
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Michael M. Ross, Mar 13 2007
STATUS
approved