OFFSET
1,2
COMMENTS
This sequence is the solution to the following problem: "Suppose you have the choice of using one of three production options: apply a simple action, bundle all existing actions (which requires p=5 steps), or apply the current bundled action. The first use of a novel bundle erases (or makes obsolete) all prior actions. How many total actions (simple) can be applied in n time steps?"
1. This problem is structurally similar to the Copy and Paste Keyboard problem: Existing sequences (A178715 and A193286) should be regarded as Paradigm-Shift Sequences with Procedural Lengths p=1 and 2, respectively.
2. The optimal number of pastes per copy, as measured by the geometric growth rate (p+z root of z), is z = 6. [Non-integer maximum between 6 and 7.]
3. The function a(n) = maximum value of the product of the terms k_i, where Sum (k_i) = n+ 5 - 5*i_max
4. All solutions will be of the form a(n) = m^b * (m+1)^d
LINKS
Jonathan T. Rowell, Solution Sequences for the Keyboard Problem and its Generalizations, Journal of Integer Sequences, Vol. 18 (2015), Article 15.10.7.
FORMULA
a(n) =
a(13) = 16 [C=2 below]
a(24) = 100 [C=3 below]
a(46) = 3750 [C=5 below]
a(57) = 22500 [C=6 below]
a(68) = 135000 [C=7 below]
a(1:68) = m^(C-R) * (m+1)^R
where C = floor((n+8)/11) [min C=1]
m = floor ((n+5)/C)-5, and R = n+5 mod C
a(n>=69) = 5^b * 6^(C-b-d) * 7^d
where C = floor((n+8)/11)
R = n+8 mod 11
b = max(0, 3-R); d = max(0, R-3)
Recursive: for n>=80, a(n)=6*a(n-11)
EXAMPLE
For n=30, C=floor(38/11)=3, m=floor(35/3)-5 = 11-5 = 6, and R= (35 mod 3) = 2; therefore a(30) = 6^(3-2)*7^2 = 6*7^2 =294.
For n=13, use the general formula with C=2 (rather than C=1), with R = (18 mod 2) = 0, m=floor(18/2)-5=9-5=4; therefore a(13)=4^2*5^0=16.
For n=80, C = floor(88/11)=8, R=(88 mod 11) = 0, b = max(0,3)=3, and d=max(0,-3)=0; therefore a(80) = 5^3*6^(8-3)*7^0 = 5^3*6^5 = 972000
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan T. Rowell, Jul 27 2011
STATUS
approved