A110431 Average of positive multiples of 3 with n decimal digits, rounded down.

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

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^(n-1)+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