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A086225 11*2^n-1. 4
10, 21, 43, 87, 175, 351, 703, 1407, 2815, 5631, 11263, 22527, 45055, 90111, 180223, 360447, 720895, 1441791, 2883583, 5767167, 11534335, 23068671, 46137343, 92274687, 184549375, 369098751, 738197503, 1476395007, 2952790015 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

[a(n-1)]^2+a(n) are perfect squares. [From Vincenzo Librandi, Aug 08 2010]

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-2).

FORMULA

a(n) = 2*a(n-1)+1.

G.f. ( 10-9*x ) / ( (2*x-1)*(x-1) ). - R. J. Mathar, Oct 22 2011

MATHEMATICA

NestList[2#+1&, 10, 30] (* or *) LinearRecurrence[{3, -2}, {10, 21}, 30] (* Harvey P. Dale, Nov 25 2013 *)

PROG

(PARI) a(n) = 11*2^n - 1 \\ Michel Marcus, Jul 15 2013

CROSSREFS

Sequence in context: A192743 A280435 A095824 * A240994 A014007 A074254

Adjacent sequences:  A086222 A086223 A086224 * A086226 A086227 A086228

KEYWORD

nonn,easy

AUTHOR

Marco Matosic, Jul 29 2003

STATUS

approved

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Last modified March 28 07:54 EDT 2017. Contains 284182 sequences.