|
| |
|
|
A126719
|
|
a(n) = -n^2 + 9n + 23.
|
|
7
|
|
|
|
23, 31, 37, 41, 43, 43, 41, 37, 31, 23, 13, 1, -13, -29, -47, -67, -89, -113, -139, -167, -197, -229, -263, -299, -337, -377, -419, -463, -509, -557, -607, -659, -713, -769, -827, -887, -949, -1013, -1079, -1147, -1217, -1289, -1363, -1439, -1517, -1597, -1679, -1763, -1849, -1937, -2027, -2119, -2213
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
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
|
a(n) = 3*a(n-1)-3*a(n-2)+a(n-3), a(0)=23, a(1)=31, a(2)=37. [Harvey P. Dale, Oct 19 2011]
G.f.: ((38-13*x)*x-23)/(x-1)^3. [Harvey P. Dale, Oct 19 2011]
|
|
|
EXAMPLE
|
For n=8, -1*8^2 + 9*8 + 23 = 31.
|
|
|
MAPLE
|
A126719:=n->-n^2+9*n+23: seq(A126719(n), n=0..100); # Wesley Ivan Hurt, Jan 20 2017
|
|
|
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
|
Cf. A126665.
Sequence in context: A036267 A107934 A155107 * A110677 A169640 A026051
Adjacent sequences: A126716 A126717 A126718 * A126720 A126721 A126722
|
|
|
KEYWORD
|
sign,easy
|
|
|
AUTHOR
|
Michael M. Ross, Mar 13 2007
|
|
|
STATUS
|
approved
|
| |
|
|
