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A192814 Constant term in the reduction of the polynomial (2*x+1)^n by x^3 -> x^2 + x + 1.  See Comments. 3
1, 1, 1, 9, 49, 225, 1041, 4873, 22817, 106753, 499425, 2336585, 10931921, 51145825, 239289457, 1119533257, 5237818689, 24505519873, 114650876097, 536402551689, 2509598769265, 11741342323937, 54932733173713, 257006830281609 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

For discussions of polynomial reduction, see A192232 and A192744.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (5,-3,7).

FORMULA

a(n) = 5*a(n-1) - 3*a(n-2) + 7*a(n-3).

G.f.: (1 -4*x -x^2) / (1 -5*x +3*x^2 -7*x^3). - R. J. Mathar, May 06 2014

MAPLE

seq(coeff(series((1-4*x-x^2)/(1-5*x+3*x^2-7*x^3), x, n+1), x, n), n = 0 .. 25); # Muniru A Asiru, Jan 03 2019

MATHEMATICA

q = x^3; s = x^2 + x + 1; z = 40;

p[n_, x_] := (2 x + 1)^n;

Table[Expand[p[n, x]], {n, 0, 7}]

reduce[{p1_, q_, s_, x_}] :=

FixedPoint[(s PolynomialQuotient @@ #1 +

       PolynomialRemainder @@ #1 &)[{#1, q, x}] &, p1]

t = Table[reduce[{p[n, x], q, s, x}], {n, 0, z}];

u1 = Table[Coefficient[Part[t, n], x, 0], {n, 1, z}] (* A192814 *)

u2 = Table[Coefficient[Part[t, n], x, 1], {n, 1, z}] (* A192815 *)

u2 = u2/2  (* A192816 *)

LinearRecurrence[{5, -3, 7}, {1, 1, 1}, 30] (* G. C. Greubel, Jan 03 2019 *)

PROG

(PARI) my(x='x+O('x^30)); Vec((1-4*x-x^2)/(1-5*x+3*x^2-7*x^3)) \\ G. C. Greubel, Jan 03 2019

(MAGMA) m:=30; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!( (1-4*x-x^2)/(1-5*x+3*x^2-7*x^3) )); // G. C. Greubel, Jan 03 2019

(Sage) ((1-4*x-x^2)/(1-5*x+3*x^2-7*x^3)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Jan 03 2019

(GAP) a:=[1, 1, 1];; for n in [4..25] do a[n]:=5*a[n-1]-3*a[n-2]+7*a[n-3]; od; Print(a); # Muniru A Asiru, Jan 03 2019

CROSSREFS

Cf. A192744, A192232, A192815.

Sequence in context: A012248 A080026 A060867 * A228018 A081655 A181539

Adjacent sequences:  A192811 A192812 A192813 * A192815 A192816 A192817

KEYWORD

nonn

AUTHOR

Clark Kimberling, Jul 10 2011

STATUS

approved

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Last modified November 18 12:35 EST 2019. Contains 329261 sequences. (Running on oeis4.)