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A242923 Lexicographically least sequence over the positive integers with the property that there are no two consecutive blocks of the same length and same sum. 2
1, 2, 1, 3, 1, 2, 1, 4, 2, 1, 2, 5, 2, 1, 3, 1, 2, 1, 3, 4, 1, 2, 1, 7, 2, 3, 1, 2, 1, 5, 1, 2, 1, 8, 2, 4, 2, 3, 2, 1, 5, 4, 3, 7, 2, 1, 4, 2, 5, 3, 1, 2, 1, 3, 4, 1, 2, 1, 4, 5, 3, 2, 1, 7, 4, 6, 2, 6, 3, 6, 1, 6, 2, 3, 2, 1, 2, 8, 3, 1, 2, 1, 3, 1, 2, 7, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

FORMULA

a(9) = 2 because choosing a(9) = 1 gives the blocks (3,1,2) and (1,4,1), which are both of length 3 and sum to 6.

MAPLE

b:= proc(n) option remember; local i, t, ok;

      if n<2 then n

    else for t from 1+b(n-1) do ok:=true;

           for i to n/2 while ok

             do ok:=b(n-2*i)+t <> 2*b(n-i) od;

           if ok then return t fi

         od

      fi

    end:

a:= n-> b(n) -b(n-1):

seq(a(n), n=1..120);  # Alois P. Heinz, May 26 2014

CROSSREFS

First difference of A242921.

Sequence in context: A285324 A308551 A194550 * A065704 A325565 A286552

Adjacent sequences:  A242920 A242921 A242922 * A242924 A242925 A242926

KEYWORD

nonn

AUTHOR

Jeffrey Shallit, May 26 2014

STATUS

approved

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Last modified September 27 03:21 EDT 2020. Contains 337380 sequences. (Running on oeis4.)