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.

Showing 1-7 of 7 results.

A173380 Number of n-step walks on square lattice (no points repeated, no adjacent points unless consecutive in path).

Original entry on oeis.org

1, 4, 12, 28, 68, 164, 396, 940, 2244, 5324, 12668, 29940, 71012, 167468, 396172, 932628, 2201636, 5175268, 12195660, 28632804, 67374292, 158017740, 371354012, 870197548, 2042809996, 4783292988, 11218303476, 26250429540, 61514573604, 143857013260, 336865512780, 787374453524, 1842579846180
Offset: 0

Views

Author

Joseph Myers, Nov 22 2010

Keywords

Comments

Fisher and Hiley give 396204 as their last term instead of 396172 (see A002932). Douglas McNeil confirms 396172 (see seqfan discussion).
Comment from N. J. A. Sloane, Nov 27 2010: Joseph Myers has discovered that several of the sequences listed by Fisher and Riley (1961) contained errors. R. J. Mathar comments that this article has 62 citations in http://adsabs.harvard.edu/abs/1961JChPh..34.1253F and that clicking through these with the "Citations to the Article (62)" button is one way to check the numbers by searching for corrections.
From Petros Hadjicostas, Jan 01 2019: (Start)
Nemirovsky et al. (1992), for a d-dimensional hypercubic lattice, define C_{n,m} to be "the number of configurations of an n-bond self-avoiding chain with m neighbor contacts." For d=2 (square lattice) and m=0 (no neighbor contacts), we have (for the current sequence) a(n) = C(n, m=0). These values (from n=1 to n=11) are listed in Table I (p. 1088) in the paper.
According to Eq. (5), p. 1090, in the above paper, for a general d, the partition number C_{n,m} satisfies C_{n,m} = Sum_{l=1..n} 2^l*l!*Bin(d,l)*p_{n,m}^{(l)}, where the coefficients p_{n,m}^{(l)} (l=1,2,...) are independent of d. For d=2 (square lattice), this becomes C_{n,m} = Sum_{l=1..n} 2^l*l!*Bin(2,l)*p_{n,m}^{(l)}.
According to Eq. (7a) and (7b), p. 1093, in the paper, p_{n,0}^{(1)} = 1 = p_{n,0}^{(n)}, p_{n,m}^{(1)} = 0 for m >= 1, and p_{n,m}^{(l)} = 0 for m >= 1 and n-m+1 <= l <= n.
Now, assume d=2. Since p_{n,0}^{(1)} = 1 for n >= 1, we have C_{1,0} = 2^1*1!*Bin(2,1)*1 = 4, while C_{n,0} = 4 + 2^2*2!*Bin(2,2)*p_{n,0}^{(2)} = 4 + 8*p_{n,0}^{(2)} for n >= 2. The partition numbers p_{n,0}^{(2)} appear in Table II, p. 1093, in the paper. We have p_{n,0}^{(2)} = A038746(n) (with p_{1,0}^{(2)} = 0 to make the formula C_{n,0} = 4 + 8*p_{n,0}^{(2)} valid even for n=1).
(End)

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Crossrefs

Cf. A002932, A002934, A033155, A033323, A034006, A038746, A042949, A046788, A047057, A174319.

Programs

Formula

a(n) = 4 + 8*A038746(n) for n>=1.

Extensions

a(23)-a(32) from Bert Dobbelaere, Jan 02 2019
a(33)-a(35) from Scott R. Shannon, Aug 25 2020

A174319 Number of n-step walks on cubic lattice (no points repeated, no adjacent points unless consecutive in path).

Original entry on oeis.org

1, 6, 30, 126, 534, 2214, 9246, 38142, 157974, 649086, 2675022, 10966470, 45054630, 184400910, 755930958, 3089851782, 12645783414, 51635728518, 211059485310, 861083848998, 3516072837894, 14334995983614, 58485689950254
Offset: 0

Views

Author

Joseph Myers, Nov 27 2010

Keywords

Comments

Fisher and Hiley give 2674926 as their last term instead of 2675022 (see A002934). Douglas McNeil confirms the correction on the seqfan list.
In the notation of Nemirovsky et al. (1992), a(n), the n-th term of the current sequence is C_{n,m} with m=0 (and d=3). Here, for a d-dimensional hypercubic lattice, C_{n,m} is "the number of configurations of an n-bond self-avoiding chain with m neighbor contacts." (Let n >= 1. For d=2, we have C(n,0) = A173380(n); for d=4, we have C(n,0) = A034006(n); and for d=5, we have C(n,0) = A038726(n).) - Petros Hadjicostas, Jan 03 2019

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Crossrefs

Cf. A002934, A038746, A038748.

Formula

a(n) = 6 + 24*A038746(n) + 48*A038748(n) for n >= 1. (It follows from Eq. (5), p. 1090, in Nemirovsky et al. (1992).) - Petros Hadjicostas, Jan 01 2019

Extensions

a(16)-a(22) from Bert Dobbelaere, Jan 03 2019

A034006 Number of n-step self-avoiding walks on the 4-dimensional hypercubic lattice with no non-contiguous adjacencies.

Original entry on oeis.org

1, 8, 56, 344, 2120, 12872, 78392, 472952, 2861768, 17223224, 103835096, 623927912, 3753164744, 22526613176, 135308002424, 811435356200, 4868892591752
Offset: 0

Views

Author

N. J. A. Sloane

Keywords

Comments

In the notation of Nemirovsky et al. (1992), a(n), the n-th term of the current sequence is C_{n,m} with m=0 (and d=4). Here, for a d-dimensional hypercubic lattice, C_{n,m} is "the number of configurations of an n-bond self-avoiding chain with m neighbor contacts." (For d=2, we have C(n,0) = A173380(n), while for d=3, we have C(n,0) = A174319(n).) - Petros Hadjicostas, Jan 02 2019

Links

Crossrefs

Cf. A038746, A038748, A173380, A174319, A323037.

Formula

a(n) = 8 + 48*A038746(n) + 192*A038748(n) + 384*A323037(n). (It can be proved using Eq. (5) in Nemirovsky et al. (1992).) - Petros Hadjicostas, Jan 02 2019

Extensions

Name edited by Petros Hadjicostas, Jan 01 2019
Title clarified, a(0), and a(12)-a(16) from Sean A. Irvine, Jul 29 2020

A038748 Coefficients arising in the enumeration of configurations of linear chains.

Original entry on oeis.org

0, 0, 1, 7, 36, 168, 736, 3151, 13190, 54938, 226597, 934200, 3831219, 15723801, 64313623, 263316219, 1075420890, 4396310382, 17937457304, 73247306563, 298635873550, 1218428664338
Offset: 1

Views

Author

N. J. A. Sloane, May 02 2000

Keywords

Comments

In the notation of Nemirovsky et al. (1992), a(n), the n-th term of the current sequence, is equal to p_{n,m}^{(l)} with m = 0 and l = 3. - Petros Hadjicostas, Jan 02 2019
This counts non-self-intersecting paths of length n on the cubic lattice, start and end points distinguished, planar paths not counted, rotations and reflections of a path not counted as distinct from that path. No points repeated, no adjacent points allowed unless consecutive in path. - Bert Dobbelaere, Jan 03 2019

Examples

			From _Bert Dobbelaere_, Jan 03 2019: (Start)
Using strings to represent a path with characters X,Y,Z for steps in positive directions and x,y,z for steps in negative directions along the respective axes, the following enumerations correspond to the first nonzero terms:
a(3) = 1: { XYZ }
a(4) = 7: { XXYZ, XYXZ, XYYZ, XYZX, XYZx, XYZY, XYZZ }
a(5) = 36: {
      XXXYZ, XXYXZ, XXYYZ, XXYZX, XXYZx, XXYZY, XXYZZ, XYXXZ, XYXYZ,
      XYXZX, XYXZY, XYXZy, XYXZZ, XYYXZ, XYYxZ, XYYYZ, XYYZX, XYYZx,
      XYYZY, XYYZZ, XYZXX, XYZXY, XYZXy, XYZXZ, XYZxx, XYZxY, XYZxZ,
      XYZYX, XYZYx, XYZYY, XYZYZ, XYZZX, XYZZx, XYZZY, XYZZy, XYZZZ }
Symmetries are avoided by imposing the following restrictions: all patterns start with 'X'. First occurrence of 'Y' comes before the first occurrence of 'Z' (presence mandatory). First occurrence of steps in negative directions (presence optional) comes after the first occurrence of the corresponding steps in positive directions.
(End)

Links

Crossrefs

Cf. A002934, A174319, A323063.

Extensions

Terms a(12) to a(15) were calculated by Petros Hadjicostas, Jan 01 2019 using Eq. (5) in Nemirovsky et al. (1992) and the terms of the sequences A038746 and A174319.
a(12)-a(15) confirmed by direct computation and a(16)-a(22) from Bert Dobbelaere, Jan 03 2019

A038726 The number of n-step self-avoiding walks in a 5-dimensional hypercubic lattice with no non-contiguous adjacencies.

Original entry on oeis.org

1, 10, 90, 730, 5930, 47690, 384090, 3075610, 24663210, 197117210, 1576845050, 12589411530, 100567197770, 802350892730, 6403639865530
Offset: 0

Views

Author

N. J. A. Sloane, May 02 2000

Keywords

Comments

In the notation of Nemirovsky et al. (1992), a(n), the n-th term of the current sequence is C_{n,m} with m=0 (and d=5). Here, for a d-dimensional hypercubic lattice, C_{n,m} is "the number of configurations of an n-bond self-avoiding chain with m neighbor contacts." (For d=2, we have C(n,0) = A173380(n); for d=3, we have C(n,0) = A174319(n); and for d=4, we have C(n,0) = A034006(n).) - Petros Hadjicostas, Jan 02 2019

Links

Crossrefs

Cf. A034006, A038746, A038748, A173380, A174319, A323037, A323063.

Formula

a(n) = 10 + 80*A038746(n) + 480*A038748(n) + 1920*A323037(n) + 3840*A323063(n). (It can be proved using Eq. (5), p. 1090, in the paper by Nemirovsky et al. (1992).) - Petros Hadjicostas, Jan 03 2019

Extensions

Name edited by Petros Hadjicostas, Jan 02 2019
Title clarified, a(0), and a(12)-a(14) from Sean A. Irvine, Jul 29 2020

A323037 Coefficients arising in the enumeration of configurations of linear chains.

Original entry on oeis.org

0, 0, 0, 1, 13, 114, 849, 5842, 38174, 242737, 1511046
Offset: 1

Views

Author

Petros Hadjicostas, Jan 02 2019

Keywords

Comments

In the notation of Nemirovsky et al. (1992), a(n), the n-th term of the current sequence, is equal to p_{n,m}^{(l)} with m = 0 and l = 4. This sequence appears in Table II, p. 1094 in the paper. (We have p_{n,0}^{(2)} = A038746(n) and p_{n,0}^{(3)} = A038748(n).)

Links

Crossrefs

Cf. A034006, A038746, A038748, A323063.

A323063 Coefficients arising in the enumeration of configurations of linear chains.

Original entry on oeis.org

0, 0, 0, 0, 1, 21, 282, 3102, 30583, 282368, 2494567
Offset: 1

Views

Author

Petros Hadjicostas, Jan 03 2019

Keywords

Comments

In the notation of Nemirovsky et al. (1992), a(n), the n-th term of the current sequence, is equal to p_{n,m}^{(l)} with m = 0 and l = 5.
For a possible interpretation of this sequence (in the context of a 5-dimensional hypercubic lattice), see the comments by Bert Dobbelaere for the sequence A038748 about a cubic lattice.
We have p_{n,0}^{(2)} = A038746(n), p_{n,0}^{(3)} = A038748(n), and p_{n,0}^{(4)} = A323037(n). For p_{n,0}^{(l)} for l = 6..10, see Table II (p. 1094) in the paper by Nemirovsky et al. (1992).

Links

Crossrefs

Cf. A038726, A038729, A038746, A038748, A323037.
Showing 1-7 of 7 results.

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