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A110380 a(n) = min{p + q + r + ...} where p,q,r,... are distinct unary numbers - containing only ones, i.e., of the form (10^k - 1)/9 - formed by using a total of n ones. 2
1, 11, 12, 112, 122, 123, 1123, 1223, 1233, 1234, 11234, 12234, 12334, 12344, 12345, 112345, 122345, 123345, 123445, 123455, 123456, 1123456, 1223456, 1233456, 1234456, 1234556, 1234566, 1234567, 11234567, 12234567, 12334567, 12344567 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Fred Schneider, Table of n, a(n) for n = 1..5000

EXAMPLE

Using n ones and only the + sign we get the following sums:

  a(1) = 1;

  a(2) = 11;

  a(3) = 12 = 1 + 11;

  a(4) = 112 = 1 + 111;

  a(5) = 122 = 11 + 111;

  a(6) = 123 = 1 + 11 + 111;

  a(7) = 1123 = 1 + 11 + 1111;

  a(8) = 1223 = 1 + 111 + 1111;

  a(9) = 1233 = 11 + 111 + 1111.

PROG

(Haskell)

a110380 = drop 1 fn

          where fn    = 0 : 1 : concat (fn' 2)

                fn' n = (map (+ones) (drop nv $ take (n + nv) fn)) : (fn' (n+1))

                        where ones = div (10^n -1) 9

                              nv   = div ((n-1)*(n-2)) 2

-- Fred Schneider, Sep 04 2016

CROSSREFS

Sequence in context: A110382 A095764 A296447 * A164854 A033047 A094624

Adjacent sequences:  A110377 A110378 A110379 * A110381 A110382 A110383

KEYWORD

base,easy,nonn

AUTHOR

Amarnath Murthy, Jul 25 2005

EXTENSIONS

More terms from Joshua Zucker, May 08 2006

STATUS

approved

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Last modified November 20 18:21 EST 2019. Contains 329337 sequences. (Running on oeis4.)