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A323824 a(0) = 6; thereafter a(n) = 4*a(n-1) + 1. 1
6, 25, 101, 405, 1621, 6485, 25941, 103765, 415061, 1660245, 6640981, 26563925, 106255701, 425022805, 1700091221, 6800364885, 27201459541, 108805838165, 435223352661, 1740893410645, 6963573642581, 27854294570325, 111417178281301, 445668713125205 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

Mike Warburton, Ulam-Warburton Automaton - Counting Cells with Quadratics, arXiv:1901.10565 [math.CO], 2019.

Index entries for linear recurrences with constant coefficients, signature (5,-4).

FORMULA

G.f.: (6 - 5*x) / ((1 - x)*(1 - 4*x)).

a(n) = (19*4^n - 1) / 3. - Colin Barker, Feb 01 2019

PROG

(PARI) Vec((6 - 5*x) / ((1 - x)*(1 - 4*x)) + O(x^25)) \\ Colin Barker, Feb 01 2019

(PARI) a(n) = (19*4^n - 1) / 3 \\ Colin Barker, Feb 01 2019

CROSSREFS

Sequence in context: A034347 A009121 A327504 * A037537 A253220 A037481

Adjacent sequences:  A323821 A323822 A323823 * A323825 A323826 A323827

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Feb 01 2019

STATUS

approved

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Last modified January 24 16:44 EST 2021. Contains 340411 sequences. (Running on oeis4.)