

A110431


Average of positive multiples of 3 with n decimal digits, rounded down.


1



6, 55, 550, 5500, 55000, 550000, 5500000, 55000000, 550000000, 5500000000, 55000000000, 550000000000, 5500000000000, 55000000000000, 550000000000000, 5500000000000000, 55000000000000000, 550000000000000000, 5500000000000000000
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OFFSET

1,1


COMMENTS

Subsidiary sequence: Average of positive multiples of k with n decimal digits, rounded down.


LINKS

Table of n, a(n) for n=1..19.


FORMULA

For n > 1, a(n+1) = 10 * a(n).


EXAMPLE

a(2) = average {12,15,...96,99} = floor((12+99)/2) = 55.


PROG

(PARI) a(n)=(11*10^(n1)+1)\2


CROSSREFS

Cf. A110430.
Sequence in context: A342388 A253475 A215853 * A121661 A118836 A079589
Adjacent sequences: A110428 A110429 A110430 * A110432 A110433 A110434


KEYWORD

nonn,base


AUTHOR

Amarnath Murthy, Aug 02 2005


EXTENSIONS

Corrected and extended by Joshua Zucker, May 10 2006
Formula and program from Charles R Greathouse IV, Aug 03 2010


STATUS

approved



