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A046636 Number of cubic residues mod 8^n. 1
1, 5, 37, 293, 2341, 18725, 149797, 1198373, 9586981, 76695845, 613566757, 4908534053, 39268272421, 314146179365, 2513169434917, 20105355479333, 160842843834661, 1286742750677285, 10293942005418277, 82351536043346213 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..19.

E. Wilmer and O. Schirokauer, A note on Stephan's conjecture 25

Index entries for linear recurrences with constant coefficients, signature (9,-8).

FORMULA

(4*8^n + 3)/7.

a(n)=8*a(n-1)-3 (with a(0)=1) [Vincenzo Librandi, Nov 18 2010]

a(n) = A046530(8^n) = A046630(3n). G.f. ( 1-4*x ) / ( (8*x-1)*(x-1) ). - R. J. Mathar, Feb 28 2011

a(n+1) = A226308(3n+2). - Philippe Deléham, Feb 24 2014

MATHEMATICA

a = {}; ZZ = 1; Do[ZZ = ZZ + 2^(3x); AppendTo[a, ZZ], {x, 0, 23}]; a/2 (* Zerinvary Lajos, Apr 03 2007 *)

CROSSREFS

Cf. A007583.

Sequence in context: A262410 A089303 A164595 * A091126 A066381 A078253

Adjacent sequences:  A046633 A046634 A046635 * A046637 A046638 A046639

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified May 27 07:41 EDT 2017. Contains 287198 sequences.