The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A057428 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A057428

Sign(-n): a(n) = 1 if -n > 0, = -1 if -n < 0, = 0 if n = 0.
(history; published version)

#32 by Joerg Arndt at Mon Feb 19 10:28:50 EST 2024

STATUS

editing

approved

#31 by Paolo P. Lava at Mon Feb 19 09:26:56 EST 2024

FORMULA

a(n) = -((n+2) mod (n+1)) for n >= 0. - Paolo P. Lava, Aug 28 2007

STATUS

approved

editing

#30 by N. J. A. Sloane at Sat Jun 04 14:14:08 EDT 2022

STATUS

proposed

approved

#29 by Nikolaos Pantelidis at Thu Apr 14 07:00:25 EDT 2022

STATUS

editing

proposed

Discussion

Thu Apr 21

17:07

Nikolaos Pantelidis: Changed it, thanks.

#28 by Nikolaos Pantelidis at Thu Apr 14 06:59:28 EDT 2022

FORMULA

G.f.: A(x) = -x/(1-x).

The Series reversion of g.f. f(x) = -x/A(1-x) satisfies Babbage's functional equation fis A(fA(x)) = x. - Nikolaos Pantelidis, Apr 13 2022

STATUS

proposed

editing

#27 by Michel Marcus at Wed Apr 13 23:47:53 EDT 2022

STATUS

editing

proposed

Discussion

Thu Apr 14

01:25

Joerg Arndt: "satisfies Babbage's functional equation" seems to be a bit of a moth full for "is its own inverse"

#26 by Michel Marcus at Wed Apr 13 23:47:47 EDT 2022

CROSSREFS

Cf. A057427.

STATUS

proposed

editing

#25 by Jon E. Schoenfield at Wed Apr 13 22:30:26 EDT 2022

STATUS

editing

proposed

#24 by Jon E. Schoenfield at Wed Apr 13 22:30:19 EDT 2022

FORMULA

G.f.: -x/(1-x). a(n) = -A057427(n).

a(n) = -A057427(n).

a(n) = -[((n+2) mod (n+1)], with ) for n >= 0. - Paolo P. Lava, Aug 28 2007

The g.f. f(x) = -x/(1-x) satisfies Babbage's functional equation f(f(x)) = x. - Nikolaos Pantelidis, Apr 14 13 2022

STATUS

proposed

editing

Discussion

Wed Apr 13

22:30

Jon E. Schoenfield: Date corrected.

#23 by Michel Marcus at Wed Apr 13 10:58:45 EDT 2022

STATUS

editing

proposed