cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A064364 Positive integers sorted by A001414(n), the sum of their prime divisors, as the major key and n as the minor key.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 8, 9, 7, 10, 12, 15, 16, 18, 14, 20, 24, 27, 21, 25, 30, 32, 36, 11, 28, 40, 45, 48, 54, 35, 42, 50, 60, 64, 72, 81, 13, 22, 56, 63, 75, 80, 90, 96, 108, 33, 49, 70, 84, 100, 120, 128, 135, 144, 162, 26, 44, 105, 112, 125, 126, 150, 160, 180, 192, 216, 243
Offset: 1

Views

Author

Howard A. Landman, Sep 25 2001

Keywords

Comments

This is a permutation of the positive integers.
a(1) could be taken as 0 because 1 is not a member of A001414 and one could start with a(0)=1 (see the W. Lang link).
The row length sequence of this array is A000607(n), n>=2.
If the array is [1,0,2,3,4,5,6,6,...] with offset 0 then the row length sequence is A000607(n), n>=0.
From David James Sycamore, May 11 2018: (Start)
For n > 1, a(n) is the smallest number not yet seen such that sopfr(a(n)) is the least possible integer. The sequence lists in increasing order elements of the finite sets S(k) = {x: sopfr(x)=k}, k >= 0, where sopfr(x) = 0 iff x = 1. When a(n) = A056240(k) for some k >= 2, then sopfr(a(n)) = k and a(n) is the first of A000607(k) terms, all of which have sopfr = k. (A000607(k) is the number of partitions of k into prime parts.) Consequently the sequence follows a sawtooth profile, rising from a(n) = A056240(k) to A000792(k), the greatest number with sopfr = k, then starting over with A056240(k+1) for the next larger value of sopfr. (End) [Edited by M. F. Hasler, Jan 19 2019]

Examples

			The triangle reads:
1,
(0,) (see comment in link to "first 16 rows" by W. Lang)
2,
3,
4,
5,  6,
8,  9,
7,  10, 12,
15, 16, 18,
14, 20, 24, 27,
21, 25, 30, 32, 36,
11, 28, 40, 45, 48, 54,
35, 42, 50, 60, 64, 72, 81,
13, 22, 56, 63, 75, 80, 90, 96, 108,
...
		

Crossrefs

Cf. A001414.
Cf. A000607 (row lengths), A002098 (row sums), A056240 (least = first term in the n-th row), A000792 (greatest term in the n-th row).
Cf. A257815 (inverse).

Programs

  • Haskell
    import Data.List (partition, union)
    a064364 n k = a064364_tabf !! (n-1) !! (k-1)
    a064364_row n = a064364_tabf !! (n-1)
    a064364_tabf = [1] : tail (f 1 [] 1 (map a000792 [2..])) where
       f k pqs v (w:ws) = (map snd pqs') :
         f (k + 1) (union pqs'' (zip (map a001414 us) us )) w ws where
           us = [v + 1 .. w]
           (pqs', pqs'') = partition ((== k) . fst) pqs
    a064364_list = concat a064364_tabf
    -- Reinhard Zumkeller, Jun 11 2015
    
  • Mathematica
    terms = 1000; nmax0 = 100000 (* a rough estimate of max sopfr *);
    sopfr[n_] := sopfr[n] = Total[Times @@@ FactorInteger[n]];
    f[n1_, n2_] := Which[t1 = sopfr[n1]; t2 = sopfr[n2]; t1 < t2, True, t1 == t2, n1 <= n2, True, False];
    Clear[g];
    g[nmax_] := g[nmax] = Sort[Range[nmax], f][[1 ;; terms]];
    g[nmax = nmax0];
    g[nmax += nmax0];
    While[g[nmax] != g[nmax - nmax0], Print[nmax]; nmax += nmax0];
    A064364 = g[nmax] (* Jean-François Alcover, Mar 13 2019 *)
  • PARI
    lista(nn) = {nmax = A000792(nn); v = vector(nmax, k, A001414(k)); for (n=1, nn, vn = select(x->x==n, v, 1); for (k = 1, #vn, print1(vn[k], ", ")))} \\ Michel Marcus, May 01 2018
    
  • PARI
    A064364_vec(N, k=6, L=9)={vector(N, i, if(i<7, N=i, until(A001414(N+=1)==k, ); NA056240(k)-1))} \\ To compute terms up to a given value of k=sopfr(n) and/or for large N >> 1000, it is more efficient to use code similar to lista() above, with "for(k...)" replaced by "a=concat(a, vn)". - M. F. Hasler, Jan 19 2019

Formula

If a(n) = A056240(k) for some k then a(n+A000607(k)-1) = A000792(k). - David James Sycamore, May 11 2018

Extensions

More terms from Vladeta Jovovic, Sep 27 2005

A371165 Positive integers with as many divisors (A000005) as distinct divisors of prime indices (A370820).

Original entry on oeis.org

3, 5, 11, 17, 26, 31, 35, 38, 39, 41, 49, 57, 58, 59, 65, 67, 69, 77, 83, 86, 87, 94, 109, 119, 127, 129, 133, 146, 148, 157, 158, 179, 191, 202, 206, 211, 217, 235, 237, 241, 244, 253, 274, 277, 278, 283, 284, 287, 291, 298, 303, 319, 326, 331, 333, 334, 353
Offset: 1

Views

Author

Gus Wiseman, Mar 14 2024

Keywords

Comments

A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.

Examples

			The terms together with their prime indices begin:
     3: {2}        67: {19}        158: {1,22}
     5: {3}        69: {2,9}       179: {41}
    11: {5}        77: {4,5}       191: {43}
    17: {7}        83: {23}        202: {1,26}
    26: {1,6}      86: {1,14}      206: {1,27}
    31: {11}       87: {2,10}      211: {47}
    35: {3,4}      94: {1,15}      217: {4,11}
    38: {1,8}     109: {29}        235: {3,15}
    39: {2,6}     119: {4,7}       237: {2,22}
    41: {13}      127: {31}        241: {53}
    49: {4,4}     129: {2,14}      244: {1,1,18}
    57: {2,8}     133: {4,8}       253: {5,9}
    58: {1,10}    146: {1,21}      274: {1,33}
    59: {17}      148: {1,1,12}    277: {59}
    65: {3,6}     157: {37}        278: {1,34}
		

Crossrefs

For prime factors instead of divisors on both sides we get A319899.
For prime factors on LHS we get A370802, for distinct prime factors A371177.
The RHS is A370820, for prime factors instead of divisors A303975.
For (greater than) instead of (equal) we get A371166.
For (less than) instead of (equal) we get A371167.
Partitions of this type are counted by A371172.
Other inequalities: A370348 (A371171), A371168 (A371173), A371169, A371170.
A000005 counts divisors.
A001221 counts distinct prime factors.
A027746 lists prime factors, A112798 indices, length A001222.
A239312 counts divisor-choosable partitions, ranks A368110.
A355731 counts choices of a divisor of each prime index, firsts A355732.
A370320 counts non-divisor-choosable partitions, ranks A355740.
A370814 counts divisor-choosable factorizations, complement A370813.

Programs

  • Mathematica
    Select[Range[100],Length[Divisors[#]] == Length[Union@@Divisors/@PrimePi/@First/@If[#==1,{},FactorInteger[#]]]&]

Formula

A000005(a(n)) = A370820(a(n)).

A246083 Paradigm shift sequence for (0,5) production scheme with replacement.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 66, 72, 78, 84, 90, 99, 108, 117, 126, 135, 144, 153, 162, 171, 180, 198, 216, 234, 252, 270, 297, 324, 351, 378, 405, 432, 459, 486, 513, 540, 594, 648, 702, 756, 810, 891, 972, 1053, 1134, 1215, 1296, 1377, 1458
Offset: 1

Views

Author

Jonathan T. Rowell, Aug 13 2014

Keywords

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=0 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 following 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 = 3.
4. All solutions will be of the form a(n) = (qm+r) * m^b * (m+1)^d.
5. For large n, the sequence is recursively defined.

Crossrefs

Paradigm shift sequences for q=5: A103969, A246074, A246075, A246076, A246079, A246083, A246087, A246091, A246095, A246099, A246103.
Paradigm shift sequences for p=0: A000792, A246080, A246081, A246082, A246083.

Programs

  • PARI
    Vec(x*(1 +x +x^2 +x^3 +x^4)^2 * (1 +2*x^5 +3*x^10 +x^15) / (1 -3*x^15) + O(x^100)) \\ Colin Barker, Nov 18 2016

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) = 3*a(n-15) for all n >= 25.
G.f.: x*(1 +x +x^2 +x^3 +x^4)^2 * (1 +2*x^5 +3*x^10 +x^15) / (1 -3*x^15). - Colin Barker, Nov 18 2016

A319055 Maximum product of an integer partition of n with relatively prime parts.

Original entry on oeis.org

1, 1, 2, 3, 6, 6, 12, 18, 24, 36, 54, 72, 108, 162, 216, 324, 486, 648, 972, 1458, 1944, 2916, 4374, 5832, 8748, 13122, 17496, 26244, 39366, 52488, 78732, 118098, 157464, 236196, 354294, 472392, 708588, 1062882, 1417176, 2125764, 3188646, 4251528, 6377292
Offset: 1

Views

Author

Gus Wiseman, Sep 09 2018

Keywords

Comments

After a(7), this appears to be the same as A319054.

Crossrefs

Programs

  • Mathematica
    Table[Max[Times@@@Select[IntegerPartitions[n],GCD@@#==1&]],{n,20}]

A342211 Largest number of maximal acyclic node-induced subgraphs of an n-node graph.

Original entry on oeis.org

1, 1, 3, 6, 10, 15, 22, 38, 64
Offset: 1

Views

Author

Pontus von Brömssen, Mar 05 2021

Keywords

Comments

This sequence is log-superadditive, i.e., a(m+n) >= a(m)*a(n). By Fekete's subadditive lemma, it follows that the limit of a(n)^(1/n) exists and equals the supremum of a(n)^(1/n). - Pontus von Brömssen, Mar 03 2022
a(10) >= 105.

Examples

			All optimal graphs (i.e., graphs having n nodes and a(n) maximal acyclic subgraphs) for 1 <= n <= 9 are listed below. Here, FCB(n_1, ..., n_k) denotes the full cyclic braid graph with cluster sizes n_1, ..., n_k, as defined by Morrison and Scott (2017), i.e., the graph obtained by arranging complete graphs of orders n_1, ..., n_k (in that order) in a cycle, and joining all pairs of nodes in neighboring parts with edges. (The graph in the paper by Fomin, Gaspers, Pyatkin, and Razgon, which shows that a(10) >= 105, is FCB(2, 2, 2, 2, 2).)
        n = 1: the 1-node graph;
        n = 2: the complete graph and the empty graph;
  3 <= n <= 6: the complete graph;
        n = 7: FCB(1, 2, 2, 2);
        n = 8: FCB(1, 2, 1, 2, 2);
        n = 9: FCB(1, 2, 2, 1, 3).
		

Crossrefs

Sequences of largest number of maximal induced subgraphs with a given property:
A000792 (independent sets or cliques),
this sequence (acyclic),
A342212 (bipartite),
A342213 (planar),
A342324 (chordal),
A352208 (3-colorable),
A352209 (perfect),
A352210 (2-degenerate),
A352211 (cluster graphs),
A352212 (triangle-free),
A352213 (cographs),
A352214 (claw-free),
A352215 (C_4-free),
A352216 (diamond-free).

Formula

a(m+n) >= a(m)*a(n).
1.5926... = 105^(1/10) <= lim_{n->oo} a(n)^(1/n) <= 1.8638. (Fomin, Gaspers, Pyatkin, and Razgon (2008)).

A193455 Paradigm shift sequence with procedure length p=3.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 16, 20, 25, 30, 36, 42, 49, 64, 80, 100, 125, 150, 180, 216, 256, 320, 400, 500, 625, 750, 900, 1080, 1296, 1600, 2000, 2500, 3125, 3750, 4500, 5400, 6480, 8000, 10000, 12500, 15625, 18750, 22500, 27000, 32400, 40000, 50000
Offset: 1

Views

Author

Jonathan T. Rowell, Jul 26 2011

Keywords

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=3 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 = 5. [Non-integer maximum between 4 and 5.]
3. The function a(n) = maximum value of the product of the terms k_i, where Sum (k_i) = n+ 3 - 3*i_max
4. All solutions will be of the form a(n) = m^b * (m+1)^d

Examples

			For n=20, C = floor(26/8) = 3, R = (23 mod 3) = 2, m = floor (23-9/3) = floor(14/3)=4; therefore a(20) = 4^(3-2)*5^(2) = 4*5^2 = 100.
For n=25, the same general formula is used, but C=4 (instead of 3). R=28 mod 4 =0, m = floor(28-12/4)=4; therefore a(25) = 4^4 = 256.
For n=35, C = floor(41/8)=5, R = 1, b = max(0,2)=2, d=max(0,-2)=0; therefore a(35) = 4^2*5^(5-2)*6^0 = 2000.
		

Crossrefs

Paradigm shift sequences: A000792 (p=0), A178715 (p=1), A193286 (p=2), A193455 (p=3), A193456 (p=4), A193457 (p=5).

Programs

  • Python
    def a(n):
        c=(n + 6)//8
        if n<25:
            if n<10: return n
            r=(n + 3)%c
            m=(n + 3 - 3*c)//c
            return m**(c - r)*(m + 1)**r
        elif n==25: return 256
        else:
            r=(n + 6)%8
            b=max(0, 3 - r)
            d=max(0, r - 3)
            return 4**b*5**(c - (b + d))*6**d
    print([a(n) for n in range(1, 101)]) # Indranil Ghosh, Jun 27 2017

Formula

a(n) =
a(25) = 256 [C = 4 below]
a(1:24) = m^(C-R) * (m+1)^R
where C = floor((n+6)/8) [min C=1],
R = n+3 mod C, m = floor((n+3-3*C)/C)
a(n>=26) = 4^b * 5^(C-(b+d)) * 6^d
where C = floor((n+6)/8), R = n+6 mod 8,
b = max(0,3-R), and d = max(0, R-3)
Recursive: a(n) = 5*a(n-8) for all n >= 34

A193456 Paradigm shift sequence with procedure length p=4.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 20, 25, 30, 36, 42, 49, 56, 64, 80, 100, 125, 150, 180, 216, 252, 294, 343, 400, 500, 625, 750, 900, 1080, 1296, 1512, 1764, 2058, 2500, 3125, 3750, 4500, 5400, 6480, 7776, 9072, 10584, 12500, 15625, 18750, 22500, 27000
Offset: 1

Views

Author

Jonathan T. Rowell, Jul 26 2011

Keywords

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 =4 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 5 and 6.]
3. The function a(n) = maximum value of the product of the terms k_i, where Sum (k_i) = n+ 4 - 4*i_max
4. All solutions will be of the form a(n) = m^b * (m+1)^d

Examples

			For n = 18, a(18) uses the general formula given for n in [1:67], but uses C=2 (rather than C=3).  m = floor(22/2)-4 = 7; R = 22 mod 2 = 0; therefore a(18) = 7^(2-0)*8^0 = 49
For n=37, a(37) has: C = floor(39/10) +1 = 3+1=4.  m = floor(41/4)-4 = 10-4=6, R = 41 mod 4 = 1; therefore, a(37) = 6^(4-1)*7^(1) = 6^3 *7 = 1512.
		

Crossrefs

Paradigm shift sequences: A000792, A178715, A193286, A193455, A193456, and A193457 for p=0,1,...,5.

Formula

a(n) =
a(8:10) = 8; 9; 10 [C=1 below]
a(18:20) = 49; 56; 88 [C=2 below]
a(28:29) = 294; 343 [C=3 below]
a(38:39) = 1764; 2058 [C=4 below]
a(48) = 10584 [C=5 below]
a(58) = 63504 [C=6 below]
a(1:67) = m^(C-R) * (m+1)^R
where C = floor((n+2)/10) +1 [min C=1]
m = floor ((n+4)/C)-4, and R = n+4 mod C
a(n>=68) = 5^b * 6^(C-b-d) * 7^d
where C = floor((n+2)/10) +1
R = n+2 mod 10
b = max(0, 8-R); d = max(0, R-8)
Recursive: for n>=69, a(n)=6*a(n-10)

A193457 Paradigm shift sequence with procedure length p=5.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 20, 25, 30, 36, 42, 49, 56, 64, 72, 81, 100, 125, 150, 180, 216, 252, 294, 343, 392, 448, 512, 625, 750, 900, 1080, 1296, 1512, 1764, 2058, 2401, 2744, 3136, 3750, 4500, 5400, 6480, 7776, 9072, 10584, 12348, 14406
Offset: 1

Views

Author

Jonathan T. Rowell, Jul 27 2011

Keywords

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

Examples

			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

A000792 (n>=1), A178715, A193286, A193455, A193456, and A193457 are paradigm shift sequences for p=0,1,...5 respectively.

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)

A246082 Paradigm shift sequence for (0,4) production scheme with replacement.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 42, 45, 48, 54, 60, 66, 72, 81, 90, 99, 108, 117, 126, 135, 144, 162, 180, 198, 216, 243, 270, 297, 324, 351, 378, 405, 432, 486, 540, 594, 648, 729, 810, 891, 972, 1053, 1134, 1215, 1296, 1458, 1620, 1782
Offset: 1

Views

Author

Jonathan T. Rowell, Aug 13 2014

Keywords

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=0 steps), or implement the current bundled action (which requires q=4 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 following 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 = 3.
4. All solutions will be of the form a(n) = (qm+r) * m^b * (m+1)^d.
5. For large n, the sequence is recursively defined.

Crossrefs

Paradigm shift sequences with q=4: A029750, A103969, A246074, A246078, A246082, A246086, A246090, A246094, A246098, A246102.
Paradigm shift sequences with p=0: A000792, A246080, A246081, A246082, A246083.

Programs

  • PARI
    Vec(x*(1+x)^2 * (1+x^2)^2 * (1+2*x^4+3*x^8+x^12) / (1-3*x^12) + O(x^100)) \\ Colin Barker, Nov 19 2016

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) = 3*a(n-12) for all n >= 20.
G.f.: x*(1+x)^2 * (1+x^2)^2 * (1+2*x^4+3*x^8+x^12) / (1-3*x^12). - Colin Barker, Nov 19 2016

A246080 Paradigm shift sequence for (0,2) production scheme with replacement.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 15, 18, 21, 24, 30, 36, 45, 54, 63, 72, 90, 108, 135, 162, 189, 216, 270, 324, 405, 486, 567, 648, 810, 972, 1215, 1458, 1701, 1944, 2430, 2916, 3645, 4374, 5103, 5832, 7290, 8748, 10935, 13122, 15309, 17496, 21870, 26244
Offset: 1

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Author

Jonathan T. Rowell, Aug 13 2014

Keywords

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=0 steps), or implement the current bundled action (which requires q=2 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 following 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 = 3.
4. All solutions will be of the form a(n) = (qm+r) * m^b * (m+1)^d.

Crossrefs

Paradigm shift sequences with q=2: A029744, A029747, A246080, A246084, A246088, A246092, A246096, A246100.
Paradigm shift sequences with p=0: A000792, A246080, A246081, A246082, A246083.

Programs

  • PARI
    Vec(x*(1+x)^2 * (1+2*x^2+3*x^4+x^6) / (1-3*x^6) + O(x^100)) \\ Colin Barker, Nov 19 2016

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) = 3*a(n-6) for all n >= 10.
G.f.: x*(1+x)^2 * (1+2*x^2+3*x^4+x^6) / (1-3*x^6). - Colin Barker, Nov 19 2016
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