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.

A322128 Triangular array, read by rows: T(n,k) = denominator of binomial(n-1, n-k)/k!, 1 <= k <= n.

Original entry on oeis.org

1, 1, 2, 1, 1, 6, 1, 2, 2, 24, 1, 1, 1, 6, 120, 1, 2, 3, 12, 24, 720, 1, 1, 2, 6, 8, 120, 5040, 1, 2, 2, 24, 24, 240, 720, 40320, 1, 1, 3, 3, 12, 90, 180, 5040, 362880, 1, 2, 1, 2, 20, 40, 60, 1120, 40320, 3628800, 1, 1, 2, 1, 4, 20, 24, 336, 8064, 362880, 39916800
Offset: 1

Views

Author

Seiichi Manyama, Nov 27 2018

Keywords

Examples

			See A322127.
		

Crossrefs

Programs

  • Mathematica
    T[n_, k_] := Denominator[Binomial[n-1, n-k]/k!]; Table[T[n, k], {n,1,10}, {k,1,n}] // Flatten (* Amiram Eldar, Nov 27 2018 *)

A321382 Number of permutations of 6 copies of 1..n with no element equal to another within a distance of 1.

Original entry on oeis.org

1, 0, 2, 48852, 8437796016, 5752866855116280, 12229789732207993835280, 68139526686950961449783790480, 873795428893219442649940388795690880, 23337489207354946577030915302871598795308160
Offset: 0

Views

Author

Seiichi Manyama, Nov 28 2018

Keywords

Crossrefs

Row 6 of A322093.

Formula

a(n) = n! * A190835(n).
a(n) = Integral_{0..infinity} (Sum_{k=1..6} (-1)^(6-k) * binomial(5, 6-k) * x^k/k!)^n * exp(-x) dx.

A322095 Number of permutations of 7 copies of 1..n with no element equal to another within a distance of 1.

Original entry on oeis.org

1, 0, 2, 339720, 549023310936, 4383995385521886720, 131828993822765959468851600, 12202002913678756821228939869239920, 2988325485815656468293009880545684170044800, 1723427149081248135793318785599849462668815779427840
Offset: 0

Views

Author

Seiichi Manyama, Nov 28 2018

Keywords

Crossrefs

Row 7 of A322093.

Formula

a(n) = n! * A190836(n).
a(n) = Integral_{0..infinity} (Sum_{k=1..7} (-1)^(7-k) * binomial(6, 7-k) * x^k/k!)^n * exp(-x) dx.

A322096 Number of permutations of 8 copies of 1..n with no element equal to another within a distance of 1.

Original entry on oeis.org

1, 0, 2, 2403588, 36734931452736, 3470403228952634903280, 1490944857678655357195402606800, 2315418264816304038508896461231618573280, 10937192762438008527903830198163831816546577931520
Offset: 0

Views

Author

Seiichi Manyama, Nov 28 2018

Keywords

Crossrefs

Row 8 of A322093.

Formula

a(n) = n! * A190837(n).
a(n) = Integral_{0..infinity} (Sum_{k=1..8} (-1)^(8-k) * binomial(7, 8-k) * x^k/k!)^n * exp(-x) dx.

A322126 Number of permutations of the multiset {1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,...,n,n,n,n,n} with no two consecutive terms equal.

Original entry on oeis.org

1, 0, 2, 7188, 134631576, 7946203275000, 1210527140790855600, 411490045733601418421040, 280031356887267221923677137280, 351026687723982522494728236869341440, 758933713536173718404757245269681913222400
Offset: 0

Views

Author

Seiichi Manyama, Nov 27 2018

Keywords

Crossrefs

Row 5 of A322093.

Programs

  • Mathematica
    a[n_] := Integrate[(x - 2 * x^2 + x^3 - 1/6 * x^4 + 1/120 * x^5)^n * Exp[-x],  {x, 0, Infinity}]; Array[a, 10, 0] (* Stefano Spezia, Nov 27 2018 *)

Formula

a(n) = n! * A190833(n).
a(n) = Integral_{0..infinity} (x - 2 * x^2 + x^3 - 1/6 * x^4 + 1/120 * x^5)^n * exp(-x) dx.

A322145 Number of permutations of 9 copies of 1..n with no element equal to another within a distance of 1.

Original entry on oeis.org

1, 0, 2, 17236524, 2511603532825176, 2829059722872229922701920, 17498057808683351584656839871450000, 459422439054082909311010463927575656038701920, 42176005899746902650961357272521722186133207293858938240
Offset: 0

Views

Author

Seiichi Manyama, Nov 28 2018

Keywords

Crossrefs

Row 9 of A322093.

Formula

a(n) = n! * A321669(n).
a(n) = Integral_{0..infinity} (Sum_{k=1..9} (-1)^(9-k) * binomial(8, 9-k) * x^k/k!)^n * exp(-x) dx.

A322146 Number of permutations of 10 copies of 1..n with no element equal to another within a distance of 1.

Original entry on oeis.org

1, 0, 2, 124948668, 174702663548149248, 2360719028641481267959955040, 211490077066069537208795610578715159120, 94446414948214202156311984061437135600678877848560
Offset: 0

Views

Author

Seiichi Manyama, Nov 28 2018

Keywords

Crossrefs

Row 10 of A322093.

Formula

a(n) = n! * A321670(n).
a(n) = Integral_{0..infinity} (Sum_{k=1..10} (-1)^(10-k) * binomial(9, 10-k) * x^k/k!)^n * exp(-x) dx.
Showing 1-7 of 7 results.