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A001489
a(n) = -n.
16
0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26, -27, -28, -29, -30, -31, -32, -33, -34, -35, -36, -37, -38, -39, -40, -41, -42, -43, -44, -45, -46, -47, -48, -49, -50, -51, -52, -53, -54, -55, -56, -57, -58, -59, -60, -61, -62, -63, -64, -65
OFFSET
0,3
COMMENTS
Also: the nonpositive integers, listed with offset = 0 and in decreasing order.
An involution: the function is its own inverse, A001489 o A001489 = A001477, the identity function on N = {0, 1, 2, 3, ...}. - M. F. Hasler, Jan 18 2015
LINKS
FORMULA
a(n) = -n.
G.f.: -x/(1-x)^2.
a(n) = -a(-n) for all n in Z. - Michael Somos, Aug 04 2018
EXAMPLE
G.f. = -x - 2*x^2 - 3*x^3 - 4*x^4 - 5*x^5 - 6*x^6 - 7*x^7 - ... - Michael Somos, Aug 04 2018
MAPLE
A001489 := n->-n;
[ seq(-n, n=0..100) ];
MATHEMATICA
Table[ -n, {n, 0, 50}] (* Stefan Steinerberger, Apr 01 2006 *)
PROG
(PARI) a(n)=-n \\ Charles R Greathouse IV, Jun 04 2013
(Python)
def A001489(n): return -n # Chai Wah Wu, Nov 14 2022
CROSSREFS
Partial sums of A057428.
Sequence in context: A160356 A374012 A001478 * A038608 A105811 A209662
KEYWORD
core,sign,easy
EXTENSIONS
Edited by M. F. Hasler, Jan 18 2015
STATUS
approved