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A133344 Complexity of the number n, counting 1's and built using +, *, ^ and # representing concatenation. 1
1, 2, 3, 4, 5, 5, 6, 5, 5, 6, 2, 3, 4, 5, 6, 6, 7, 7, 7, 7, 8, 4, 5, 5, 6, 6, 6, 7 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

The complexity of an integer n is the least number of 1's needed to represent it using only additions, multiplications, exponentiation and parentheses. This allows juxtaposition of 1's to form larger integers, so for example, 2 = 1+1 has complexity 2, but unlike A003037, so does 11 = 1#1 (concatenating two 1's is an allowed operation). Similarly a(111)= 3. The complexity of a number has been defined in several different ways by different authors. See the Index to the OEIS for other definitions.

EXAMPLE

An example (usually nonunique) of the derivation of the first 24 values.

a(1) = 1, the number of 1's in "1."

a(2) = 2, the number of 1's in "1+1 = 2."

a(3) = 3, the number of 1's in "1+1+1 = 3."

a(4) = 4, the number of 1's in "1+1+1+1 = 4."

a(5) = 5, the number of 1's in "1+1+1+1+1 = 5."

a(6) = 5, since there are 5 1's in "((1+1)*(1+1+1)) = 6."

a(7) = 6, since there are 6 1's in "1+(((1+1)*(1+1+1))) = 7."

a(8) = 5, since there are 5 1's in "(1+1)^(1+1+1) = 8."

a(9) = 5, since there are 5 1's in "(1+1+1)^(1+1) = 9."

a(10) = 6 since there are 6 1's in "1+((1+1+1)^(1+1)) = ten.

a(11) = 2 since there are 2 1's in "1#1 = eleven."

a(12) = 3 since there are 3 1's in "1+(1#1) = twelve."

a(13) = 4 since there are 4 1's in "1+1+(1#1) = thirteen."

a(14) = 5 since there are 5 1's in "1+1+1+(1#1) = fourteen."

a(16) = 6 since there are 6 1's in "(1+1+1+1)^(1+1)."

a(17) = 7 since there are 7 1's in "1+((1+1+1+1)^(1+1))."

a(18) = 7 since there are 7 1's in "(1+1)*((1+1+1)^(1+1))."

a(19) = 7 since there are 7 1's in "(1#1)+((1+1)^(1+1+1))."

a(20) = 7 since there are 7 1's in "(1#1)+((1+1+1)^(1+1))."

a(21) = 8 since there are 8 1's in "1+((1#1)+((1+1+1)^(1+1)))."

a(22) = 4 since 22 = (1+1)*(1#1) = (1#1)+(1#1) = (1#1)#(1#1).

CROSSREFS

Cf. A003037, A025280, A005520, A005245, A005421, A117618.

Sequence in context: A200262 A007599 A154940 * A091334 A025280 A096365

Adjacent sequences:  A133341 A133342 A133343 * A133345 A133346 A133347

KEYWORD

base,nonn

AUTHOR

Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 20 2007

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Last modified February 16 12:41 EST 2012. Contains 205909 sequences.