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A010892 Inverse of 6th cyclotomic polynomial. A period 6 sequence. 114
1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Any sequence b(n) satisfying the recurrence b(n)=b(n-1)-b(n-2) can be written as b(n)=b(0)*a(n)+(b(1)-b(0))*a(n-1).

a(n) is the determinant of the n X n matrix M with m(i,j)=1 if |i-j| <= 1 and 0 otherwise. - Mario Catalani (mario.catalani(AT)unito.it), Jan 25 2003

Also row sum of triangle in A108299; a(n)=L(n-1,1), where L is also defined as in A108299; see A061347 for L(n,-1). - Reinhard Zumkeller, Jun 01 2005

Pisano period lengths:  1, 3, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6... - R. J. Mathar, Aug 10 2012

Periodic sequences of this type can be also calculated by a(n) = c + floor(q/(p^m-1)*p^n) mod p, where c is a constant, q is the number representing the periodic digit pattern and m is the period length. c, p and q can be calculated as follows: Let D be the array representing the number pattern to be repeated, m = size of D, max = maximum value of elements in D, min = minimum value of elements in D. Than c := min, p := max - min + 1 and q := p^m*sum_{i=1..m} (D(i)-min)/p^i. Example: D = (1, 1, 0, -1, -1, 0), c = -1, m = 6, p = 3 and q = 676 for this sequence. - Hieronymus Fischer, Jan 04 2013

B(n) = a(n+5) = S(n-1, 1) appears, together with a(n) = A057079(n+1), in the formula 2*exp(Pi*n*I/3) = A(n) + B(n)*sqrt(3)*I with I = sqrt(-1). For S(n, x) see A049310. See also a Feb 27 2014 comment on A099837. - Wolfdieter Lang, Feb 27 2014

a(n) (for n>=1) is the difference between numbers of even and odd permutations p of 1,2,..,n such that |p(i)-i|<=1 for i=1,2,..,n. - Dmitry Efimov, Jan 08 2016

From Tom Copeland, Jan 31 2016: (Start)

Specialization of the o.g.f. 1 / [(x - w1)(x-w2)] = (1/(w1-w2)) [(w1-w2) + (w1^2 - w2^2) x + (w1^3-w2^3) x^2 + ...] with w1*w2 = (1/w1) + (1/w2) = 1. Then w1 = q = e^(i*Pi/3) and w2 = 1/q = e^(-i*Pi/3), giving the o.g.f. 1 /(1-x+x^2) for this entry with a(n) = (2/sqrt(3)) sin[(n+1)Pi/3]. See the Copeland link for more relations.

a(n) = [q^(n+1) - q^(-(n+1))] / [q - q^(-1)], so this entry gives the o.g.f. for an instance of the quantum integers denoted by [m]_q in Morrison et al. and Tingley. (End)

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Paul Barry, A Catalan Transform and Related Transformations on Integer Sequences, J. Integer Sequ., Vol. 8 (2005), Article 05.4.5.

T. Copeland, Addendum to Elliptic Lie Triad

Ralph E. Griswold, Shaft Sequences

S. Morrison, E. Peters, N. Snyder, Knot polynomial identities and quantum group coincidences, arXiv preprint arXiv:1003.0022 [math.QA], 2014.

M. Somos, Rational Function Multiplicative Coefficients

P. Tingley,  A minus sign ... (Two constructions of the Jones polynomial), arXiv preprint arXiv:1002.0555v2 [math.GT], 2015.

Index entries for linear recurrences with constant coefficients, signature (1,-1).

Index entries for sequences related to Chebyshev polynomials.

Index to sequences related to inverse of cyclotomic polynomials

FORMULA

G.f.: 1 / (1 - x + x^2).

a(n) = a(n-1) - a(n-2), a(0)=1, a(1)=1.

a(n) = ((-1)^floor(n/3) + (-1)^floor((n+1)/3))/2.

a(n) = 0 if n mod 6 = 2 or 5, a(n)= + 1 if n mod 6 = 0 or 1, a(n)= -1 else. a(n) = S(n, 1) = U(n, 1/2) (Chebyshev U(n, x) polynomials).

a(n) = sqrt(4/3)*Imaginary[(1/2+i*sqrt(3/4))^(n+1)]. - Henry Bottomley, Apr 12 2000

Binomial transform of A057078. a(n) = Sum_{k=0..n} C(k, n-k)*(-1)^(n-k). - Paul Barry, Sep 13 2003

a(n) = 2*sin(Pi*n/3+Pi/3)/sqrt(3). - Paul Barry, Jan 28 2004

a(n) = Sum_{k=0..floor(n/2)} C(n-k, k)*(-1)^k. - Paul Barry, Jul 28 2004

Euler transform of length 6 sequence [ 1, -1, -1, 0, 0, 1]. - Michael Somos, Sep 23 2005

a(n) = a(1 - n) = -a(-2 - n) for all n in Z. - Michael Somos, Feb 14 2006

a(n) = -(1/6)*(n mod 6+(n+1) mod 6-((n+3) mod 6)-((n+4) mod 6)). - Paolo P. Lava, Oct 20 2006

a(n) = Sum_{k=0..n} (-2)^(n-k) * A085838(n,k). - Philippe Deléham, Oct 26 2006

a(n) = b(n+1) where b(n) is multiplicative with b(2^e) = -(-1)^e if e>0, b(3^e) = 0^e, b(p^e) = 1 if p == 1 (mod 6), b(p^e) = (-1)^e if p == 5 (mod 6). - Michael Somos, Oct 29 2006

Given g.f. A(x), then, B(x) = x * A(x) satisfies 0 = f(B(x), B(x^2)) where f(u, v) = u^2 - v - 2*u*v * (1 - u). - Michael Somos, Oct 29 2006

a(2*n) = A057078(n), a(2*n+1) = A049347(n).

a(n) = Sum_{k=0..n} A109466(n,k). - Philippe Deléham, Nov 14 2006

a(n) = Sum_{k=0..n} A133607(n,k). - Philippe Deléham, Dec 30 2007

a(n) = A128834(n+1). - Jaume Oliver Lafont, Dec 05 2008

a(n) = Sum_{k=0..n} C(n+k+1,2k+1) * (-1)^k. - Paul Barry, Jun 03 2009

a(n) = A101950(n,0) = (-1)^n * A049347(n). - Philippe Deléham, Feb 10 2012

a(n) = Product_{k=1..floor(n/2)} 1-4*(cos(k*Pi/(n+1)))^2. - Mircea Merca, Apr 01 2012

G.f.: 1 / (1 - x / (1 + x / (1 - x))). - Michael Somos, Apr 02 2012

a(n) = -1 + floor(181/819*10^(n+1)) mod 10. - Hieronymus Fischer, Jan 03 2013

a(n) = -1 + floor(13/14*3^(n+1)) mod 3. - Hieronymus Fischer, Jan 04 2013

a(n) = 1/(1+r2)*(1/r1)^n + 1/(1+r1)*(1/r2)^n, with r1=(1-i*sqrt(3))/2 and r2=(1+i*sqrt(3))/2. - Ralf Stephan, Jul 19 2013

a(n) = ((n+1)^2 mod 3) * (-1)^floor((n+1)/3). - Wesley Ivan Hurt, Mar 15 2015

a(n-1) = n - Sum_{i=1..n-1} i*a(n-i). - Derek Orr, Apr 28 2015

EXAMPLE

G.f. = 1 + x - x^3 - x^4 + x^6 + x^7 - x^9 - x^10 + x^12 + x^13 - x^15 + ...

MAPLE

a:=n->coeftayl(1/(x^2-x+1), x=0, n);

a:=n->2*sin(Pi*(n+1)/3)/sqrt(3);

A010892:=n->[1, 1, 0, -1, -1, 0][irem(n, 6)+1];

A010892:=n->Array(0..5, [1, 1, 0, -1, -1, 0])[irem(n, 6)];

A010892:=n->table([0=1, 1=1, 2=0, 3=-1, 4=-1, 5=0])[irem(n, 6)];

with(numtheory, cyclotomic); c := series(1/cyclotomic(6, x), x, 102): seq(coeff(c, x, n), n=0..101); # Rainer Rosenthal, Jan 01 2007

MATHEMATICA

a[n_] := {1, 1, 0, -1, -1, 0}[[Mod[n, 6] + 1]]; Table[a[n], {n, 0, 101}] (* Jean-François Alcover, Jul 19 2013 *)

CoefficientList[Series[1/Cyclotomic[6, x], {x, 0, 100}], x] (* Vincenzo Librandi, Apr 03 2014 *)

PROG

(PARI) {a(n) = (-1)^(n\3) * sign((n + 1)%3)}; /* Michael Somos, Sep 23 2005 */

(PARI) {a(n) = subst( poltchebi(n) + poltchebi(n-1), 'x, 1/2) * 2/3}; /* Michael Somos, Sep 23 2005 */

(PARI) {a(n) = [ 1, 1, 0, -1, -1, 0][n%6 + 1]}; /* Michael Somos, Feb 14 2006

(PARI) {a(n) = local(A, p, e); if( n<0, 0, n++; A = factor(n); prod( k=1, matsize(A)[1], if( p=A[k, 1], e=A[k, 2]; if( p==2, -(-1)^e, if( p==3, 0, if(p%6==1, 1, (-1)^e))))))}; /* Michael Somos, Oct 29 2006 */

(Python)

def A010892(n): return [1, 1, 0, -1, -1, 0][n%6] # Alec Mihailovs, Jan 01 2007

(Sage) [lucas_number1(n, 1, +1) for n in xrange(-5, 97)] # Zerinvary Lajos, Apr 22 2009

(Sage)

def A010892():

    x, y = -1, -1

    while true:

        yield -x

        x, y = y, -x + y

a = A010892(); [a.next() for i in range(40)]  # Peter Luschny, Jul 11 2013

(MAGMA) &cat[[1, 1, 0, -1, -1, 0]: n in [0..20]]; // Vincenzo Librandi, Apr 03 2014

CROSSREFS

a(n) = row sums of signed triangle A049310.

Cf. A049347, A057078.

Differs only by a shift from A128834.

Sequence in context: A117441 A049347 * A091338 A016345 A016148 A016333

Adjacent sequences:  A010889 A010890 A010891 * A010893 A010894 A010895

KEYWORD

sign,easy,mult

AUTHOR

Simon Plouffe

EXTENSIONS

Entry revised by N. J. A. Sloane, Jul 16 2004

STATUS

approved

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Last modified April 26 15:40 EDT 2017. Contains 285446 sequences.