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.

Previous Showing 51-60 of 110 results. Next

A246096 Paradigm shift sequence for (4,2) production scheme with replacement.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 21, 24, 28, 32, 36, 40, 45, 50, 55, 60, 66, 72, 84, 96, 112, 128, 144, 160, 180, 200, 225, 250, 275, 300, 336, 384, 448, 512, 576, 640, 720, 800, 900, 1000, 1125, 1250, 1375, 1536, 1792, 2048, 2304, 2560, 2880, 3200, 3600, 4000, 4500, 5000, 5625, 6250, 7168, 8192, 9216, 10240, 11520, 12800, 14400, 16000, 18000, 20000, 22500, 25000
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=4 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 = 4.
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=4: A193456, A246096, A246097, A246098, A246099.

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) ).
Recursive: a(n) = 4*a(n-12) for all n >= 67.

A246100 Paradigm shift sequence for (5,2) 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, 21, 24, 28, 32, 36, 40, 45, 50, 55, 60, 66, 72, 78, 84, 96, 112, 128, 144, 160, 180, 200, 225, 250, 275, 300, 330, 360, 396, 448, 512, 576, 640, 720, 800, 900, 1000, 1125, 1250, 1375, 1500, 1650, 1800, 2048, 2304, 2560, 2880, 3200, 3600, 4000, 4500, 5000, 5625, 6250, 6875, 7500, 8250, 9216, 10240, 11520, 12800, 14400, 16000, 18000, 20000, 22500, 25000, 28125, 31250, 34375, 37500, 41250, 46080, 51200, 57600, 64000, 72000, 80000, 90000, 100000, 112500, 125000, 140625, 156250
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=5 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 = 5.
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=5: A193457, A246100, A246101, A246102, A246103.

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) ).
Recursive: a(n) = 5*a(n-15) for all n >= 75.

A364494 Numbers k such that k divides A163511(k).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 32, 36, 48, 64, 72, 96, 105, 128, 144, 192, 210, 256, 288, 384, 420, 429, 512, 576, 768, 840, 858, 1024, 1152, 1365, 1536, 1617, 1680, 1716, 2048, 2304, 2730, 3072, 3234, 3360, 3432, 3887, 4096, 4235, 4608, 5460, 6144, 6468, 6720, 6864, 7774, 8192, 8470, 9216, 10829, 10920, 12288
Offset: 1

Views

Author

Antti Karttunen, Jul 27 2023

Keywords

Comments

If n is present, then 2*n is also present, and vice versa.
A007283 is included as a subsequence, because it gives the known fixed points of map n -> A163511(n).

Crossrefs

Positions of 1's in A364491.
Cf. A163511.
Subsequences: A007283, A029744, A364495 (odd terms).
Cf. also A364295, A364496, A364497.

Programs

A056486 a(n) = (9*2^n + (-2)^n)/4 for n>0.

Original entry on oeis.org

4, 10, 16, 40, 64, 160, 256, 640, 1024, 2560, 4096, 10240, 16384, 40960, 65536, 163840, 262144, 655360, 1048576, 2621440, 4194304, 10485760, 16777216, 41943040, 67108864, 167772160, 268435456, 671088640, 1073741824, 2684354560, 4294967296, 10737418240
Offset: 1

Views

Author

Keywords

Comments

Old name was: "Number of periodic palindromes using a maximum of four different symbols".
Number of necklaces with n beads and 4 colors that are the same when turned over and hence have reflection symmetry. - Herbert Kociemba, Nov 24 2016

Examples

			G.f. = 4*x + 10*x^2 + 16*x^3 + 40*x^4 + 64*x^5 + 160*x^6 + 256*x^7 + 640*x^8 + ...
For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome.
		

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Column 4 of A284855.

Programs

  • Magma
    [(9*2^n + (-2)^n)/4 : n in [1..50]]; // Wesley Ivan Hurt, Nov 24 2016
    
  • Maple
    A056486:=n->(9*2^n + (-2)^n)/4: seq(A056486(n), n=1..50); # Wesley Ivan Hurt, Nov 24 2016
  • Mathematica
    CoefficientList[Series[-1+(1+4*x+6*x^2)/(1-4*x^2),{x,0,30}],x] (* Herbert Kociemba, Nov 24 2016 *)
    k=4; Table[(k^Floor[(n+1)/2] + k^Ceiling[(n+1)/2]) / 2, {n, 1, 30}] (* Robert A. Russell, Sep 21 2018 *)
  • PARI
    a(n) = (9*2^n+(-2)^n)/4; \\ Altug Alkan, Sep 21 2018
    
  • SageMath
    [2^(n-2)*(9+(-1)^n) for n in range(1,51)] # G. C. Greubel, Mar 23 2024

Formula

a(n) = 4^((n+1)/2) for n odd, a(n) = 4^(n/2)*5/2 for n even.
From Colin Barker, Jul 08 2012: (Start)
a(n) = 4*a(n-2).
G.f.: 2*x*(2+5*x)/((1-2*x)*(1+2*x)). (End)
G.f.: -1 + (1+4*x+6*x^2)/(1-4*x^2). - Herbert Kociemba, Nov 24 2016
E.g.f.: 5*sinh(x)^2 + 2*sinh(2*x). - Ilya Gutkovskiy, Nov 24 2016
a(n) = ( 4^floor((n+1)/2) + 4^ceiling((n+1)/2) )/2. - Robert A. Russell, Sep 21 2018

Extensions

Better name from Ralf Stephan, Jul 18 2013

A056493 Number of primitive (period n) periodic palindromes using a maximum of two different symbols.

Original entry on oeis.org

2, 1, 2, 3, 6, 7, 14, 18, 28, 39, 62, 81, 126, 175, 246, 360, 510, 728, 1022, 1485, 2030, 3007, 4094, 6030, 8184, 12159, 16352, 24381, 32766, 48849, 65534, 97920, 131006, 196095, 262122, 392364, 524286, 785407, 1048446, 1571310, 2097150, 3143497
Offset: 1

Views

Author

Keywords

Comments

For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome.
Also number of aperiodic necklaces (Lyndon words) with two colors that are the same when turned over.

Examples

			a(1) = 2 with aaa... and bbb..., a(2) = 1 with ababab..., a(3) = 2 with aabaab... and abbabb..., a(4) = 3 with aaabaaab... and aabbaabb... and abbbabbb.... - _Michael Somos_, Nov 29 2016
		

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for a pdf file of Chap. 2]

Crossrefs

Column 2 of A284856.

Programs

  • Mathematica
    mx=40;gf[x_,k_]:=Sum[ MoebiusMu[n]*Sum[Binomial[k,i]x^(n i),{i,0,2}]/( 1-k x^(2n)),{n,mx}]; CoefficientList[Series[gf[x,2],{x,0,mx}],x] (* Herbert Kociemba, Nov 29 2016 *)

Formula

Sum_{d|n} mu(d)*b(n/d), where b(n) = A029744(n+1). [Corrected by Petros Hadjicostas, Oct 15 2017. The original formula referred to a previous version of sequence A029744 that had a different offset.]
More generally, let gf(k) be the g.f. for the number of necklaces with reflectional symmetry but no rotational symmetry and beads of k colors. Then gf(k): Sum_{n >= 1} mu(n)*Sum_{i=0..2} binomial(k,i)*x^(n*i)/(1 - k*x^(2*n)). - Herbert Kociemba, Nov 29 2016
G.f.: Sum_{n >= 1} mu(n)*x^n*(2 + 3*x^n)/(1 - 2*x^(2*n)). The g.f. by Herbet Kociemba above, with k = 2, becomes Sum_{n>=1} mu(n)*(x^n + 1)^2/(1 - 2*x^(2*n)). The two formulae differ by the "undetermined" constant Sum_{n >= 1} mu(n). - Petros Hadjicostas, Oct 15 2017

Extensions

More terms and additional comments from Christian G. Bower, Jun 22 2000

A246088 Paradigm shift sequence for (2,2) production scheme with replacement.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 18, 21, 24, 28, 32, 36, 40, 45, 54, 63, 72, 84, 96, 112, 128, 144, 162, 189, 216, 252, 288, 336, 384, 448, 512, 576, 648, 756, 864, 1008, 1152, 1344, 1536, 1792, 2048, 2304, 2592, 3024, 3456, 4032, 4608, 5376, 6144, 7168, 8192, 9216, 10368, 12096, 13824, 16128, 18432, 21504, 24576, 28672, 32768, 36864, 41472
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=2 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 = 4.
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=2: A193286, A246088, A246089, A246090, A246091.

Programs

  • PARI
    Vec(x*(1 +2*x +3*x^2 +4*x^3 +5*x^4 +6*x^5 +7*x^6 +8*x^7 +9*x^8 +10*x^9 +7*x^10 +4*x^11 +3*x^12 +2*x^13 +x^14 +x^20 +6*x^21 +3*x^22 +2*x^29 +9*x^30) / ((1 -2*x^5) * (1 +2*x^5)) + 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) = 4*a(n-10) for all n >= 32.
G.f.: x*(1 +2*x +3*x^2 +4*x^3 +5*x^4 +6*x^5 +7*x^6 +8*x^7 +9*x^8 +10*x^9 +7*x^10 +4*x^11 +3*x^12 +2*x^13 +x^14 +x^20 +6*x^21 +3*x^22 +2*x^29 +9*x^30) / ((1 -2*x^5) * (1 +2*x^5)). - Colin Barker, Nov 19 2016

A193652 A020988 and A007583 interleaved.

Original entry on oeis.org

0, 1, 2, 3, 10, 11, 42, 43, 170, 171, 682, 683, 2730, 2731, 10922, 10923, 43690, 43691, 174762, 174763, 699050, 699051, 2796202, 2796203, 11184810, 11184811, 44739242, 44739243, 178956970, 178956971, 715827882, 715827883, 2863311530, 2863311531, 11453246122
Offset: 0

Views

Author

Reinhard Zumkeller, Aug 08 2011

Keywords

Comments

a(2*n) = A020988(n), a(2*n+1) = a(2*n) + 1 = A007583(n);
apart from initial zero, record values in A048985: a(n)=A048985(A029744(n)) and a(n)<A048985(m) for m<A029744(n).

Programs

Formula

a(n) = 2 * (4^floor(n/2) - 1) / 3 + n mod 2.
G.f.: ( -x*(-1-2*x+2*x^2) ) / ( (x-1)*(2*x+1)*(2*x-1)*(1+x) ). - R. J. Mathar, Feb 19 2015

Extensions

Terms corrected by R. J. Mathar, Feb 19 2015

A209727 T(n,k) = 1/4 the number of (n+1) X (k+1) 0..2 arrays with every 2 X 2 subblock having distinct clockwise edge differences.

Original entry on oeis.org

2, 3, 3, 4, 4, 4, 6, 5, 5, 6, 8, 7, 6, 7, 8, 12, 9, 8, 8, 9, 12, 16, 13, 10, 10, 10, 13, 16, 24, 17, 14, 12, 12, 14, 17, 24, 32, 25, 18, 16, 14, 16, 18, 25, 32, 48, 33, 26, 20, 18, 18, 20, 26, 33, 48, 64, 49, 34, 28, 22, 22, 22, 28, 34, 49, 64, 96, 65, 50, 36, 30, 26, 26, 30, 36, 50, 65, 96
Offset: 1

Views

Author

R. H. Hardin, Mar 12 2012

Keywords

Comments

Table starts
..2..3..4..6..8.12.16.24.32.48.64..96.128.192.256.384.512.768.1024.1536.2048
..3..4..5..7..9.13.17.25.33.49.65..97.129.193.257.385.513.769.1025.1537.2049
..4..5..6..8.10.14.18.26.34.50.66..98.130.194.258.386.514.770.1026.1538.2050
..6..7..8.10.12.16.20.28.36.52.68.100.132.196.260.388.516.772.1028.1540.2052
..8..9.10.12.14.18.22.30.38.54.70.102.134.198.262.390.518.774.1030.1542.2054
.12.13.14.16.18.22.26.34.42.58.74.106.138.202.266.394.522.778.1034.1546.2058
.16.17.18.20.22.26.30.38.46.62.78.110.142.206.270.398.526.782.1038.1550.2062
.24.25.26.28.30.34.38.46.54.70.86.118.150.214.278.406.534.790.1046.1558.2070

Examples

			Some solutions for n=4, k=3
..2..1..2..1....0..2..0..1....1..2..0..2....0..1..0..2....2..1..2..1
..0..2..0..2....2..1..2..0....2..0..1..0....2..0..2..1....0..2..0..2
..1..0..1..0....0..2..0..1....1..2..0..2....0..1..0..2....1..0..1..0
..0..2..0..2....2..1..2..0....2..0..1..0....2..0..2..1....0..2..0..2
..1..0..1..0....0..2..0..1....1..2..0..2....0..1..0..2....2..1..2..1
		

Crossrefs

Column 1 is A029744(n+1).
Diagonal is A027383.

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-2).
k=2..7: a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3).

A275717 Numbers n for which A003961(n) > A003961(n-1).

Original entry on oeis.org

2, 3, 4, 6, 8, 12, 14, 15, 16, 18, 20, 24, 26, 27, 30, 32, 35, 36, 38, 39, 40, 42, 44, 45, 48, 50, 52, 54, 56, 60, 62, 63, 64, 66, 68, 70, 72, 74, 75, 78, 80, 81, 84, 86, 87, 88, 90, 92, 95, 96, 98, 100, 102, 104, 108, 110, 112, 114, 116, 117, 119, 120, 122, 123, 124, 125, 126, 128, 130, 132, 135, 138, 140, 143, 144
Offset: 1

Views

Author

Antti Karttunen, Aug 07 2016

Keywords

Comments

One more than the positions of ascents in permutation A048673.

Crossrefs

One more than A275721.
Complement: A275718 (apart from 1 which is in neither sequence).
Cf. A029744 (a subsequence, apart from its initial 1).

Programs

  • Mathematica
    f[n_] := Times @@ Map[Prime[PrimePi@ First[#] + 1]^Last[#] &, FactorInteger@ n]; Select[Range@ 145, f[# - 1] < f@ # &] (* Michael De Vlieger, Aug 07 2016 *)

A116451 Numbers having fewer prime factors than at least one smaller number.

Original entry on oeis.org

5, 7, 9, 10, 11, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82
Offset: 0

Views

Author

Reinhard Zumkeller, Feb 16 2006

Keywords

Comments

Complement of A029744.
Numbers whose odd part is greater than 3. - Peter Munn, Aug 12 2020

Crossrefs

Formula

A116452(n) = A001222(a(n)).

Extensions

The offset should really be 1, since this is a list, but that change would also require a complete rewrite of A116454, plus changes to A116453. So for the moment let's leave this with offset 0. - N. J. A. Sloane, Aug 17 2020
Previous Showing 51-60 of 110 results. Next