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A163662 A020988 written in base 2. 3
10, 1010, 101010, 10101010, 1010101010, 101010101010, 10101010101010, 1010101010101010, 101010101010101010, 10101010101010101010, 1010101010101010101010, 101010101010101010101010, 10101010101010101010101010, 1010101010101010101010101010 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The digits are n concatenated blocks of (10).

Smallest number having alternating bit sum -n. Cf. A065359. - Washington Bomfim, Jan 22 2011

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..495

Index entries for linear recurrences with constant coefficients, signature (101, -100).

FORMULA

a(n) = Sum_{k=1,...,n} 10^(2k-1).

From R. J. Mathar, Jul 08 2009: (Start)

a(n) = 100*a(n-1) + 10.

a(n) = 101*a(n-1) - 100*a(n-2).

G.f.: 10*x/((100*x-1)*(x-1)). (End)

From G. C. Greubel, Aug 01 2017: (Start)

a(n) = (10/99)*(10^(2*n) - 1).

E.g.f.: (10/99)*(exp(100*x) - exp(x)). (End)

MAPLE

A163662 := proc(n) add(10^(2*k-1), k=1..n) ; end: seq(A163662(n), n=1..30) ; # R. J. Mathar, Jul 08 2009

MATHEMATICA

Table[(10/99)*(10^(2*n) - 1), {n, 1, 50}] (* G. C. Greubel, Aug 01 2017 *)

PROG

(PARI) x='x+O('x^50); Vec(10*x/((100*x-1)*(x-1))) \\ G. C. Greubel, Aug 01 2017

CROSSREFS

Sequence in context: A106456 A079214 A176067 * A080070 A080120 A274069

Adjacent sequences:  A163659 A163660 A163661 * A163663 A163664 A163665

KEYWORD

nonn,base,easy

AUTHOR

Jaroslav Krizek, Aug 02 2009

STATUS

approved

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Last modified September 21 15:25 EDT 2017. Contains 292300 sequences.