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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A323856 Sum of square displacements over all self-avoiding n-step walks on 4-d cubic lattice with first step specified, A242355(n)/8.

Original entry on oeis.org

1, 16, 177, 1696, 14995, 126180, 1025707, 8133544, 63274143, 484966972, 3672258385, 27533213880, 204715798387, 1511417062948, 11090886972237, 80957709527896, 588206815480213, 4256231985648516, 30685328305245631, 220504966309520728, 1579874958814261407
Offset: 1

Views

Author

Hugo Pfoertner, Feb 03 2019

Keywords

Examples

			a(1) = 1 is the square displacement of the fixed initial step.
a(2) = 16, because one of the A010575(2)/8 = 7 end points is (2,0,0,0) with square distance 4 and the other 6 end points (1,-1,0,0), (1,1,0,0), (1,0,-1,0), (1,0,1,0), (1,0,0,-1), (1,0,0,1) all have square distance 2. 16 = 1*4 + 6*2.
a(3) = 177, because there are 6 end points with square distance 1, e.g., (0,1,0,0), 24 end points with square distance 3, e.g., (1,1,1,0), 18 end points with square distance 5, e.g., (2,1,0,0), and 1 end point with square distance 9, (3,0,0,0). 177 = 6*1 + 24*3 + 18*5 + 1*9.
		

References

Crossrefs

A323857 Sum of end-to-end Manhattan distances over all self-avoiding n-step walks on 4-d cubic lattice.

Original entry on oeis.org

1, 14, 135, 1144, 9083, 69690, 522781, 3864524, 28243251, 204687550, 1473038447, 10542725976, 75096139471, 532846305962, 3767808141891, 26566180648012, 186826646453453
Offset: 1

Views

Author

Hugo Pfoertner, Feb 03 2019

Keywords

Comments

The first step is kept fixed, i.e., (0,0,0,0) -> (1,0,0,0).

Examples

			a(3) = 135, because there are 6 (of A010575(3)/8=49) end points with Manhattan distance 1, (0,-1,0,0), (0,1,0,0), (0,0,-1,0), (0,0,1,0), (0,0,0,-1), (0,0,0,1), and the remaining 43 end points all have Manhattan distance 3, e.g., (3,0,0,0), (2,-1,0,0), ..., (1,-1,-1,0), ... 135 = 6*1 + 43*3.
		

Crossrefs

A374397 a(n) is the number of 4-step self avoiding walks in the n-dimensional hypercubic lattice that start at the origin.

Original entry on oeis.org

2, 100, 726, 2696, 7210, 15852, 30590, 53776, 88146, 136820, 203302, 291480, 405626, 550396, 730830, 952352, 1220770, 1542276, 1923446, 2371240, 2893002, 3496460, 4189726, 4981296, 5880050, 6895252, 8036550, 9313976, 10737946, 12319260, 14069102, 15999040, 18121026
Offset: 1

Views

Author

Johann Peters, Jul 07 2024

Keywords

Comments

We have the formula below because we have 2*n choices for the first step, and (2*n-1)^3 choices for the next three, but have counted exactly 2*n*(2*n-1)*(2*n-2) self-intersecting walks.

References

  • N. Madras and G. Slade, "The Self Avoiding Walk", Birkhäuser, 2013.

Crossrefs

Cf. A010575.

Programs

  • Mathematica
    A374397[n_] := 2*n*(4*n*(n - 1)*(2*n - 1) + 1);
    Array[A374397, 50] (* or *)
    LinearRecurrence[{5, -10, 10, -5, 1}, {2, 100, 726, 2696, 7210}, 50] (* Paolo Xausa, Sep 23 2024 *)

Formula

a(n) = 16*n^4 - 24*n^3 + 8*n^2 + 2*n.
G.f.: 2*x*(1 + 45*x + 123*x^2 + 23*x^3)/(1 - x)^5. - Stefano Spezia, Jul 07 2024
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