A192779 - OEIS

A192779

Coefficient of x^2 in the reduction of the n-th Fibonacci polynomial by x^3->x^2+3x+1.

0, 0, 1, 1, 7, 12, 47, 107, 337, 868, 2520, 6808, 19192, 52756, 147185, 407069, 1131599, 3136292, 8707655, 24151335, 67025633, 185946904, 515971328, 1431563056, 3972149312, 11021051864, 30579529249, 84846231017, 235416993159, 653192251196

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OFFSET

1,5

COMMENTS

For discussions of polynomial reduction, see A192232 and A192744.

LINKS

Table of n, a(n) for n=1..30.

Index entries for linear recurrences with constant coefficients, signature (1,6,-1,-6,1,1).

FORMULA

a(n)=a(n-1)+6*a(n-2)-a(n-3)-6*a(n-4)+a(n-5)+a(n-6).

G.f.: -x^3/((x^2-x-1)*(x^4+2*x^3-3*x^2-2*x+1)). [Colin Barker, Nov 23 2012]

EXAMPLE

The first five polynomials p(n,x) and their reductions:

F1(x)=1 -> 1

F2(x)=x -> x

F3(x)=x^2+1 -> x^2+1

F4(x)=x^3+2x -> x^2+5x+1

F5(x)=x^4+3x^2+1 -> 7x^2+4x+2, so that

A192777=(1,0,1,1,2,...), A192778=(0,1,0,5,4,...), A192779=(0,0,1,1,7,...)

MATHEMATICA

(See A192777.)

LinearRecurrence[{1, 6, -1, -6, 1, 1}, {0, 0, 1, 1, 7, 12}, 30] (* Harvey P. Dale, Oct 29 2018 *)

CROSSREFS

Cf. A192744, A192232, A192616, A192772, A192777.

Sequence in context: A335579 A178681 A194264 * A108238 A038278 A266056

Adjacent sequences: A192776 A192777 A192778 * A192780 A192781 A192782

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jul 09 2011

STATUS

approved