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 incremental action, bundle existing output as an integrated product (which requires p=-4 steps), or implement the current bundled action (which requires q=5 steps). The first use of a novel bundle erases (or makes obsolete) all prior actions. How large an output can be generated in n time steps?"
1. A production scheme with replacement R(p,q) eliminates existing output followinging a bundling action, while an additive scheme A(p,q) retains the output. The schemes correspond according to A(p,q)=R(p-q,q), with the replacement scheme serving as the default presentation.
2. 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 production schemes R(1,1) and R(2,1) with replacement, respectively.
3. The ideal number of implementations per bundle, as measured by the geometric growth rate (p+zq root of z), is z = 2.
4. All solutions will be of the form a(n) = (qm+r) * m^b * (m+1)^d.
5. The paradigm shift sequence for the R(-4,5) scheme is also the solution to the R(-2,4) scheme.
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,2).
FORMULA
a(n) = (qd+r) * d^(C-R) * (d+1)^R, where r = (n-Cp) mod q, Q = floor( (R-Cp)/q ), R = Q mod (C+1), and d = floor ( Q/(C+1) ).
a(n) = 2*a(n-6) for all n >= 12.
G.f.: x*(1+x)^2 * (1-x+x^2)^2 * (1+x+x^2)^2 / (1-2*x^6). - Colin Barker, Nov 18 2016
MATHEMATICA
Join[{1, 2, 3, 4, 5}, LinearRecurrence[{0, 0, 0, 0, 0, 2}, {6, 7, 8, 9, 10, 11}, 64]] (* Jean-François Alcover, Sep 25 2017 *)
PROG
(PARI) Vec(x*(1+x)^2 * (1-x+x^2)^2 * (1+x+x^2)^2 / (1-2*x^6) + O(x^100)) \\ Colin Barker, Nov 18 2016
CROSSREFS
Paradigm shift sequences with implementation step q=5: A103969, A246074, A246075, A246076, A246079, A246083, A246087, A246091, A246095, A246099, A246103.
KEYWORD
nonn,easy
AUTHOR
Jonathan T. Rowell, Aug 13 2014
STATUS
approved