

A100047


A Chebyshev transform of the Fibonacci numbers.


52



0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,1


COMMENTS

Multiplicative with a(p^e) = 1^(e+1) if p = 2, 0 if p = 5, 1 if p == 1 or 9 (mod 10), 1^e if p == 3 or 7 (mod 10).  David W. Wilson, Jun 10 2005
This sequence is a divisibility sequence, i.e., a(n) divides a(m) whenever n divides m. Case P1 = 1, P2 = 1, Q = 1 of the 3 parameter family of 4thorder linear divisibility sequences found by Williams and Guy.  Peter Bala, Mar 24 2014
From Peter Bala, Mar 24 2014: (Start)
This is the particular case P1 = 1, P2 = 1, Q = 1 of the following results:
Let P1, P2 and Q be integers. Let alpha and beta denote the roots of the quadratic equation x^2  1/2*P1*x + 1/4*P2 = 0. Let T(n,x;Q) denote the bivariate Chebyshev polynomial of the first kind defined by T(n,x;Q) = 1/2*( (x + sqrt(x^2  Q))^n + (x  sqrt(x^2  Q))^n ) (when Q = 1, T(n,x;Q) reduces to the ordinary Chebyshev polynomial of the first kind T(n,x)). Then we have
1) The sequence A(n) := ( T(n,alpha;Q)  T(n,beta;Q) )/(alpha  beta) is a linear divisibility sequence of the fourth order.
2) A(n) belongs to the 3parameter family of fourthorder divisibility sequences found by Williams and Guy.
3) The o.g.f. of the sequence A(n) is the rational function x*(1  Q*x^2)/(1  P1*x + (P2 + 2*Q)*x^2  P1*Q*x^3 + Q^2*x^4).
4) The o.g.f. is the Chebyshev transform of the rational function x/(1  P1*x + P2*x^2), where the Chebyshev transform takes the function A(x) to the function (1  Q*x^2)/(1 + Q*x^2)*A(x/(1 + Q*x^2)).
5) Let q = sqrt(Q) and set a = sqrt( q + (P2)/(4*q) + (P1)/2 ) and b = sqrt( q + (P2)/(4*q)  (P1)/2 ). Then the o.g.f. of the sequence A(n) is the Hadamard product of the rational functions x/(1  (a + b)*x + q*x^2) and x/(1  (a  b)*x + q*x^2). Thus A(n) is the product of two (usually, noninteger) Lucastype sequences.
6) A(n) = the bottom left entry of the 2 X 2 matrix 2*T(n,1/2*M;Q), where M is the 2 X 2 matrix [0, P2; 1, P1].
For examples of the above see A006238, A054493, A078070, A092184, A098306, A100048, A108196, A138573, A152090 and A218134. (End)


LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000
Peter Bala, Linear divisibility sequences and Chebyshev polynomials
TianXiao He, Peter J.S. Shiue, An Approach to the Construction of Linear Divisibility Sequences of Higher Orders, Journal of Integer Sequences, Vol. 20 (2017), Article 17.8.2.
H. C. Williams and R. K. Guy, Some fourthorder linear divisibility sequences, Intl. J. Number Theory 7 (5) (2011) 12551277.
H. C. Williams and R. K. Guy, Some Monoapparitic Fourth Order Linear Divisibility Sequences Integers, Volume 12A (2012) The John Selfridge Memorial Volume
Index entries for linear recurrences with constant coefficients, signature (1,1,1,1).


FORMULA

G.f.: x(1x^2)/(1x+x^2x^3+x^4).
a(n) = a(n1)  a(n2) + a(n3)  a(n4).
a(n) = n*Sum_{k=0..floor(n/2)} (1)^k *binomial(nk,k)*A000045(n2*k)/(nk).
From Peter Bala, Mar 24 2014: (Start)
a(n) = ( T(n,alpha)  T(n,beta) )/(alpha  beta), where alpha = (1 + sqrt(5))/4 and beta = (1  sqrt(5))/4 and T(n,x) denotes the Chebyshev polynomial of the first kind.
a(n) = bottom left entry of the matrix T(n, M), where M is the 2 X 2 matrix [0, 1/4; 1, 1/2].
The o.g.f. is the Hadamard product of the rational functions x/(1  1/2*(sqrt(5) + 1)*x + x^2) and x/(1  1/2*(sqrt(5)  1)*x + x^2). (End)
Euler transform of length 10 sequence [ 1, 2, 0, 0, 1, 0, 0, 0, 0, 1].  Michael Somos, May 24 2015
a(n) = a(n) = a(n + 5) for all n in Z.  Michael Somos, May 24 2015
A011558(n) = A080891(n) = a(n) = A244895(n).  Michael Somos, May 24 2015


EXAMPLE

A Chebyshev transform of the Fibonacci numbers A000045: if A(x) is the g.f. of a sequence, map it to ((1x^2)/(1+x^2))A(x/(1+x^2)).
The denominator is the 10th cyclotomic polynomial.
G.f. = x + x^2  x^3  x^4  x^6  x^7 + x^8 + x^9 + x^11 + x^12  x^13 + ...


MATHEMATICA

a[ n_] := {1, 1, 1, 1, 0, 1, 1, 1, 1, 0}[[Mod[ n, 10, 1]]]; (* Michael Somos, May 24 2015 *)
a[ n_] := (1)^Quotient[ n, 5] Sign[ Mod[ n, 5, 2]]; (* Michael Somos, May 24 2015 *)
a[ n_] := (1)^Quotient[n, 5] {1, 1, 1, 1, 0}[[Mod[ n, 5, 1]]]; (* Michael Somos, May 24 2015 *)


PROG

(PARI) {a(n) = (1)^(n\5) * [0, 1, 1, 1, 1][n%5+1]}; /* Michael Somos, May 24 2015 */
(PARI) {a(n) = (1)^(n\5) * sign( centerlift( Mod(n, 5)))}; /* Michael Somos, May 24 2015 */


CROSSREFS

Cf. A099443, A011655, A100048. A006238, A054493, A078070, A092184, A098306, A108196, A138573, A152090, A218134.
Cf. A011558, A080891, A244895.
Sequence in context: A092248 A106743 A244895 * A080891 A011558 A112713
Adjacent sequences: A100044 A100045 A100046 * A100048 A100049 A100050


KEYWORD

easy,sign,mult


AUTHOR

Paul Barry, Oct 31 2004


STATUS

approved



