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A110430 Arithmetic mean of all n-digit positive even numbers. 2
5, 54, 549, 5499, 54999, 549999, 5499999, 54999999, 549999999, 5499999999, 54999999999, 549999999999, 5499999999999, 54999999999999, 549999999999999, 5499999999999999, 54999999999999999, 549999999999999999, 5499999999999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..18.

FORMULA

a(n) =1/2{10^(n-1) + 10^n -2}

EXAMPLE

a(2) = Arithmetic mean of 10,12,14,...96,98 =(10 + 98)/2 =54.

MATHEMATICA

Table[FromDigits[PadRight[{5, 4}, n, 9]], {n, 20}] (* Harvey P. Dale, Apr 24 2020 *)

CROSSREFS

Sequence in context: A268882 A229298 A087125 * A110432 A215542 A304322

Adjacent sequences: A110427 A110428 A110429 * A110431 A110432 A110433

KEYWORD

base,easy,nonn

AUTHOR

Amarnath Murthy, Aug 02 2005

EXTENSIONS

Corrected and extended by Joshua Zucker, May 10 2006

STATUS

approved

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Last modified November 26 20:01 EST 2022. Contains 358362 sequences. (Running on oeis4.)