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 1-10 of 18 results. Next

A209656 Meandric numbers for a river crossing up to 12 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 63, 155, 448, 1152, 3452, 9158, 28178, 76538, 240368, 665100, 2123379, 5964156, 19301178, 54890366, 179679030, 516360755, 1706896545, 4949350203, 16500278295, 48216373545, 161946759019, 476447428528, 1610847688579, 4767486352733, 16213635060406
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 12 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Column k=12 of A380367.
Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21) onwards from Andrew Howroyd, Jan 31 2025

A204352 Meandric numbers for a river crossing up to 3 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 9, 21, 52, 131, 345, 915, 2519, 6926, 19711, 55674, 162594, 468929, 1398129, 4100003, 12433282, 36960316, 113678461, 341785050, 1063890616, 3229522688, 10156518859, 31085477306, 98635931623, 304048850048, 972323924567, 3015979607106, 9711570455824
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross 3 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Column k=3 of A380367.
Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(40) from Andrew Howroyd, Dec 07 2015

A206432 Meandric numbers for a river crossing any number of parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 63, 155, 448, 1152, 3452, 9158, 28178, 76539, 240370, 665129, 2123439, 5964691, 19302316, 54898417, 179696559, 516468945, 1707136837, 4950706599, 16503343162, 48232630706, 161984048816, 476636485050, 1611287098347, 4769639932874, 16218699278307
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross any number of parallel East-West roads n times.
Of course, the number of roads crossed cannot be more than the number of crossings, n.
A file (28GB) listing all solutions through n=20 is available from the author.

Links

Crossrefs

Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(30) from Andrew Howroyd, Dec 07 2015

A208062 Meandric numbers for a river crossing up to 4 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 22, 61, 142, 420, 1017, 3146, 7844, 25083, 63974, 209875, 545060, 1824949, 4810138, 16374993, 43695535, 150820899, 406669871, 1420155120, 3863613980, 13627843933, 37363313071, 132933980698, 366939582498, 1315436809855, 3652777067949, 13182411646150
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 4 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(36) from Andrew Howroyd, Dec 05 2015

A208126 Meandric numbers for a river crossing up to 5 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 62, 153, 433, 1120, 3281, 8776, 26399, 72423, 222496, 622616, 1946044, 5533227, 17545134, 50545069, 162237507, 472541542, 1532707268, 4506042037, 14748997812, 43709690021, 144213436887, 430371626111, 1429980808522, 4293569179189, 14355812667699
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 5 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(36) from Andrew Howroyd, Dec 05 2015

A208452 Meandric numbers for a river crossing up to 6 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 63, 154, 446, 1135, 3416, 8947, 27712, 74204, 235041, 640552, 2065849, 5711840, 18696838, 52321747, 173413647, 490279035, 1642287831, 4684178185, 15834649146, 45511151647, 155077912223, 448722569787, 1539743907074, 4481866870316, 15474663284941
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 6 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(36) from Andrew Howroyd, Dec 05 2015

A208453 Meandric numbers for a river crossing up to 7 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 63, 155, 447, 1150, 3433, 9118, 27923, 75981, 237379, 658380, 2090519, 5888530, 18951534, 54069881, 176020213, 507632647, 1668910009, 4857449082, 16106998656, 47253245257, 157874165288, 466367068388, 1568587476660, 4661900731148, 15773729508730
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 7 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(36) from Andrew Howroyd, Dec 05 2015

A209383 Meandric numbers for a river crossing up to 8 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 63, 155, 448, 1151, 3450, 9137, 28134, 76236, 239712, 661374, 2115046, 5921549, 19203568, 54422726, 178585838, 511343777, 1694965469, 4896195579, 16371992897, 47656781437, 160578870274, 470571482142, 1596323368095, 4705798878362, 16059653893209
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 8 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(36) from Andrew Howroyd, Dec 05 2015

A209621 Meandric numbers for a river crossing up to 9 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 63, 155, 448, 1152, 3451, 9156, 28155, 76491, 240015, 664363, 2118804, 5954414, 19246816, 54772539, 179063855, 515006165, 1700131496, 4934242781, 16427135058, 48050970367, 161163698861, 474656662565, 1602509174036, 4748224219223, 16125057102402
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 9 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21)-a(36) from Andrew Howroyd, Dec 06 2015

A209626 Meandric numbers for a river crossing up to 11 parallel roads at n points.

Original entry on oeis.org

1, 1, 2, 4, 10, 23, 63, 155, 448, 1152, 3452, 9158, 28177, 76537, 240343, 665073, 2122968, 5963685, 19295541, 54883588, 179608831, 516272903, 1706070421, 4948280698, 16490889347, 48203859456, 161842379157, 476304741819, 1609703418480, 4765887074059, 16201200791291
Offset: 0

Views

Author

Robert Price, May 07 2012

Keywords

Comments

Number of ways that a river (or directed line) that starts in the South and flows East can cross up to 11 parallel East-West roads n times.
Sequence derived from list of solutions described in A206432.

Links

Crossrefs

Column k=11 of A380367.
Cf. A005316 (sequence for one road; extensive references and links).
Cf. A076876 (sequence for two parallel roads).
Cf. A204352, A208062, A208126, A208452, A208453, A209383, A209621, A209622, A209626, A209656, A209657, A209660, A209707, A210344, A210478, A210567, A210592 (sequences for 3 to 19 parallel roads).
Cf. A206432 (sequence for unlimited number of parallel roads).
Cf. A076875, A076906, A076907.

Extensions

a(21) onwards from Andrew Howroyd, Jan 31 2025
Showing 1-10 of 18 results. Next

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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