|
| |
|
|
A057427
|
|
Sign(n): a(n) = 1 if n>0, = -1 if n<0, = 0 if n = 0.
|
|
67
| |
|
|
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,1
|
|
|
COMMENTS
| For nonnegative n, partial sums of A063524 (characteristic function of 1). - Jeremy Gardiner, Sep 08 2002
For nonnegative n, characteristic function of positive integers. - Franklin T. Adams-Watters, Aug 01 2011.
Number of binary bracelets of n beads, 0 of them 0. Number of binary bracelets of n beads, 1 of them 0. Number of binary bracelets of n beads, 0 of them 0, with 00 prohibited. For n>=2, a(n-1) is the number of binary bracelets of n beads, one of them 0, with 00 prohibited. [From Washington Bomfim, Aug 27 2008]
a(A000027(n)) = 1; a(A000004(n)) = 0. [From Reinhard Zumkeller, Oct 11 2008]
Central terms of the triangle in A152487. [From Reinhard Zumkeller, Dec 06 2008]
n-th prime mod 2 (with offset 1,1). [From Philippe DELEHAM, Apr 04 2009]
Also decimal expansion of 1/9. - Vincenzo Librandi, Sep 24 2011
Also parity of the prime numbers A000040, (with offset 1). - Omar E. Pol, Jan 17 2012
|
|
|
REFERENCES
| T. M. Macrobert, Functions of a Complex Variable, 4th ed., Macmillan and Co, London, 1958, p. 90
|
|
|
LINKS
| Index entries for sequences related to linear recurrences with constant coefficients
Index entries for characteristic functions
Vincenzo Librandi, Table of n, a(n) for n = 0..200
|
|
|
FORMULA
| G.f.: x/(1-x).
E.g.f.: exp(x)-1
G.f.: Sum_{k>=0} 2^k x^(2^k)/(1+x^(2^k)). - Michael Somos Sep 11 2005
a(n) = 1 + (-1)*A000007(n), n >= 0. - Omar E. Pol, Jan 17 2012
|
|
|
PROG
| (PARI) a(n)=sign(n)
(PARI) /* n>=0 */ a(n)=!!n [From Jaume Oliver Lafont, Mar 19 2009]
|
|
|
CROSSREFS
| Cf. A000007 (0^n). [From Jaume Oliver Lafont, Mar 19 2009]
Sequence in context: A103131 A112347 * A178334 A185016 A185015 A185014
Adjacent sequences: A057424 A057425 A057426 * A057428 A057429 A057430
|
|
|
KEYWORD
| easy,nonn,mult
|
|
|
AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Sep 05 2000
|
| |
|
|
