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A102865 Base-4 digits are, in order, the first n terms of the sequence (1, 3, 21, 203, 2021, 20203, 202021, 2020203, 20202021, 202020203, ... ). 1
1, 3, 9, 35, 137, 547, 2185, 8739, 34953, 139811, 559241, 2236963, 8947849, 35791395, 143165577, 572662307, 2290649225, 9162596899, 36650387593, 146601550371, 586406201481, 2345624805923, 9382499223689, 37529996894755, 150119987579017, 600479950316067 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..25.

Index entries for linear recurrences with constant coefficients, signature (4,1,-4).

FORMULA

4^n = a(n) + A037576(n) for n >= 1.

a(n) + a(n+1) = A039301(n+2).

a(n) = 4*a(n-1) + a(n-2) - 4*a(n-3). - Harvey P. Dale, Mar 23 2012

G.f.: 1 + x*(3-3*x-4*x^2)/((1-x)*(1+x)*(1-4*x)). - Colin Barker, Aug 28 2012

MATHEMATICA

FromDigits[IntegerDigits[#], 4]&/@(NestList[FromDigits[Flatten[ IntegerDigits[#]/.{3->{2, 1}, 1->{0, 3}}]]&, 1, 30]) (* or *) LinearRecurrence[{4, 1, -4}, {1, 3, 9}, 31](* Harvey P. Dale, Mar 23 2012 *)

CROSSREFS

Cf. A037576.

Sequence in context: A149017 A149018 A149019 * A046697 A151045 A225041

Adjacent sequences:  A102862 A102863 A102864 * A102866 A102867 A102868

KEYWORD

base,easy,nonn

AUTHOR

Creighton Dement, Mar 01 2005

EXTENSIONS

More terms from Harvey P. Dale, Mar 23 2012

STATUS

approved

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Last modified May 12 06:54 EDT 2021. Contains 343820 sequences. (Running on oeis4.)