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 10 results.

A107025 Binomial transform of the expansion of 1/(1-x^5-x^6).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 8, 29, 85, 211, 464, 938, 1808, 3459, 6826, 14198, 30960, 69143, 154433, 340006, 734561, 1561313, 3286129, 6900097, 14542101, 30855957, 65908862, 141395972, 303745077, 651763377, 1395140215, 2978858672
Offset: 0

Views

Author

Paul Barry, May 09 2005

Keywords

Comments

In general, the binomial transform of 1/(1-x^r-x^(r+1)) is given by (1-x)^r/((1-x)^(r+1)-x^r), with a(n) = Sum_{k=0..floor((n+1)/2)} binomial(n+k,(r+1)k) = Sum_{k=0..floor((r+1)n/r)} binomial(k,(r+1)n-r*k).
Number of compositions of 6*n into parts 5 and 6. - Seiichi Manyama, Jun 22 2024

Crossrefs

Formula

G.f.: (1-x)^5/((1-x)^6-x^5).
a(n) = 6a(n-1)-15a(n-2)+20a(n-3)-15a(n-4)+7a(n-5)-a(n-6).
a(n) = Sum_{k=0..floor((n+1)/2)} binomial(n+k, 6k).
a(n) = Sum_{k=0..floor(6n/5)} binomial(k, 6n-5k).
a(n) = A017837(6*n). - Seiichi Manyama, Jun 22 2024

A306713 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of g.f. 1/(1-x^k-x^(k+1)).

Original entry on oeis.org

1, 1, 1, 1, 0, 2, 1, 0, 1, 3, 1, 0, 0, 1, 5, 1, 0, 0, 1, 1, 8, 1, 0, 0, 0, 1, 2, 13, 1, 0, 0, 0, 1, 0, 2, 21, 1, 0, 0, 0, 0, 1, 1, 3, 34, 1, 0, 0, 0, 0, 1, 0, 2, 4, 55, 1, 0, 0, 0, 0, 0, 1, 0, 1, 5, 89, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 7, 144, 1, 0, 0, 0, 0, 0, 0, 1, 0, 2, 3, 9, 233
Offset: 0

Views

Author

Seiichi Manyama, Mar 05 2019

Keywords

Comments

A(n,k) is the number of compositions of n into parts k and k+1.

Examples

			Square array begins:
    1, 1, 1, 1, 1, 1, 1, 1, 1, ...
    1, 0, 0, 0, 0, 0, 0, 0, 0, ...
    2, 1, 0, 0, 0, 0, 0, 0, 0, ...
    3, 1, 1, 0, 0, 0, 0, 0, 0, ...
    5, 1, 1, 1, 0, 0, 0, 0, 0, ...
    8, 2, 0, 1, 1, 0, 0, 0, 0, ...
   13, 2, 1, 0, 1, 1, 0, 0, 0, ...
   21, 3, 2, 0, 0, 1, 1, 0, 0, ...
   34, 4, 1, 1, 0, 0, 1, 1, 0, ...
   55, 5, 1, 2, 0, 0, 0, 1, 1, ...
		

Crossrefs

Programs

  • Mathematica
    T[n_, k_] := Sum[Binomial[j, n-k*j], {j, 0, Floor[n/k]}]; Table[T[k, n - k + 1], {n, 0, 12}, {k, 0, n}] // Flatten (* Amiram Eldar, Jun 21 2021 *)

Formula

A(n,k) = Sum_{j=0..floor(n/k)} binomial(j,n-k*j).

A369794 Expansion of 1/(1 - x^5/(1-x)^6).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 6, 21, 56, 126, 253, 474, 870, 1651, 3367, 7372, 16762, 38183, 85290, 185573, 394555, 826752, 1724816, 3613968, 7642004, 16313856, 35052905, 75487110, 162349105, 348018300, 743376838, 1583718457, 3370144462, 7173308802, 15285181447
Offset: 0

Views

Author

Seiichi Manyama, Feb 01 2024

Keywords

Comments

Number of compositions of 6*n-5 into parts 5 and 6.

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(1/(1-x^5/(1-x)^6))

Formula

a(n) = A107025(n)-A107025(n-1). First differences of A107025.
a(n) = A017837(6*n-5) = Sum_{k=0..floor((6*n-5)/5)} binomial(k,6*n-5-5*k) for n > 0.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 7*a(n-5) - a(n-6) for n > 6.
a(n) = Sum_{k=0..floor(n/5)} binomial(n-1+k,n-5*k).

A099132 Quintisection of 1/(1-x^5-x^6).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 7, 22, 57, 127, 253, 464, 804, 1354, 2289, 4005, 7372, 14198, 28033, 55523, 108699, 208982, 394555, 734561, 1357136, 2504932, 4643816, 8671852, 16313856, 30855957, 58502733, 110882143, 209689343, 395358538, 743376838
Offset: 0

Views

Author

Paul Barry, Sep 29 2004

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{5,-10,10,-5,1,1},{1,1,1,1,1,1},40] (* Harvey P. Dale, Aug 20 2012 *)
  • PARI
    Vec((1-x)^4/((1-x)^5-x^6) + O(x^40)) \\ Michel Marcus, Sep 06 2017

Formula

G.f.: (1-x)^4/((1-x)^5-x^6);
a(n) = Sum_{k=0..n} binomial(k, 5(n-k));
a(n) = 5a(n-1)-10a(n-2)+10a(n-3)-5a(n-4)+a(n-5)+a(n-6);
a(n) = A017837(5n).
a(n) = Sum_{k=0..floor(n/5)} binomial(n-k, 5k). - Paul Barry, May 09 2005

A339089 Number of compositions (ordered partitions) of n into distinct parts congruent to 5 mod 6.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 4, 1, 0, 0, 0, 6, 4, 1, 0, 0, 0, 6, 6, 1, 0, 0, 0, 12, 6, 1, 0, 0, 0, 18, 8, 1, 0, 0, 24, 24, 8, 1, 0, 0, 24, 30, 10, 1, 0, 0, 48, 42, 10, 1, 0, 0, 72, 48, 12, 1, 0, 0, 120, 60, 12, 1, 0, 120, 144
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 23 2020

Keywords

Examples

			a(33) = 6 because we have [17, 11, 5], [17, 5, 11], [11, 17, 5], [11, 5, 17], [5, 17, 11] and [5, 11, 17].
		

Crossrefs

Programs

  • Mathematica
    nmax = 86; CoefficientList[Series[Sum[k! x^(k (3 k + 2))/Product[1 - x^(6 j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=0} k! * x^(k*(3*k + 2)) / Product_{j=1..k} (1 - x^(6*j)).

A373961 Number of compositions of 6*n-1 into parts 5 and 6.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 15, 44, 129, 340, 804, 1742, 3550, 7009, 13835, 28033, 58993, 128136, 282569, 622575, 1357136, 2918449, 6204578, 13104675, 27646776, 58502733, 124411595, 265807567, 569552644, 1221316021, 2616456236, 5595314908, 11944318042, 25466629978
Offset: 1

Views

Author

Seiichi Manyama, Jun 23 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\5, binomial(n+k, n-1-5*k));

Formula

a(n) = A017837(6*n-1).
a(n) = Sum_{k=0..floor(n/5)} binomial(n+k,n-1-5*k).
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 7*a(n-5) - a(n-6).
G.f.: x*(1-x)^4/((1-x)^6 - x^5).
a(n) = A373962(n+1) - A373962(n).

A373962 Number of compositions of 6*n-2 into parts 5 and 6.

Original entry on oeis.org

0, 1, 3, 6, 10, 15, 22, 37, 81, 210, 550, 1354, 3096, 6646, 13655, 27490, 55523, 114516, 242652, 525221, 1147796, 2504932, 5423381, 11627959, 24732634, 52379410, 110882143, 235293738, 501101305, 1070653949, 2291969970, 4908426206, 10503741114, 22448059156
Offset: 1

Views

Author

Seiichi Manyama, Jun 24 2024

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{6,-15,20,-15,7,-1},{0,1,3,6,10,15},40] (* Harvey P. Dale, Nov 16 2024 *)
  • PARI
    a(n) = sum(k=0, n\5, binomial(n+k, n-2-5*k));

Formula

a(n) = A017837(6*n-2).
a(n) = Sum_{k=0..floor(n/5)} binomial(n+k,n-2-5*k).
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 7*a(n-5) - a(n-6).
G.f.: x^2*(1-x)^3/((1-x)^6 - x^5).
a(n) = A373963(n+1) - A373963(n).

A373963 Number of compositions of 6*n-3 into parts 5 and 6.

Original entry on oeis.org

0, 0, 1, 4, 10, 20, 35, 57, 94, 175, 385, 935, 2289, 5385, 12031, 25686, 53176, 108699, 223215, 465867, 991088, 2138884, 4643816, 10067197, 21695156, 46427790, 98807200, 209689343, 444983081, 946084386, 2016738335, 4308708305, 9217134511, 19720875625
Offset: 1

Views

Author

Seiichi Manyama, Jun 24 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\5, binomial(n+k, n-3-5*k));

Formula

a(n) = A017837(6*n-3).
a(n) = Sum_{k=0..floor(n/5)} binomial(n+k,n-3-5*k).
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 7*a(n-5) - a(n-6).
G.f.: x^3*(1-x)^2/((1-x)^6 - x^5).
a(n) = A373964(n+1) - A373964(n).

A373964 Number of compositions of 6*n-4 into parts 5 and 6.

Original entry on oeis.org

0, 0, 0, 1, 5, 15, 35, 70, 127, 221, 396, 781, 1716, 4005, 9390, 21421, 47107, 100283, 208982, 432197, 898064, 1889152, 4028036, 8671852, 18739049, 40434205, 86861995, 185669195, 395358538, 840341619, 1786426005, 3803164340, 8111872645, 17329007156
Offset: 1

Views

Author

Seiichi Manyama, Jun 24 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\5, binomial(n+k, n-4-5*k));

Formula

a(n) = A017837(6*n-4).
a(n) = Sum_{k=0..floor(n/5)} binomial(n+k,n-4-5*k).
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 7*a(n-5) - a(n-6).
G.f.: x^4*(1-x)/((1-x)^6 - x^5).
a(n) = A369794(n+1) - A369794(n).

A127840 a(1)=1, a(2)=...=a(6)=0, a(n) = a(n-6)+a(n-5) for n>6.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 2, 1, 0, 0, 1, 3, 3, 1, 0, 1, 4, 6, 4, 1, 1, 5, 10, 10, 5, 2, 6, 15, 20, 15, 7, 8, 21, 35, 35, 22, 15, 29, 56, 70, 57, 37, 44, 85, 126, 127, 94, 81, 129, 211, 253, 221, 175, 210, 340, 464, 474, 396, 385, 550
Offset: 1

Views

Author

Stephen Suter (sms5064(AT)psu.edu), Apr 02 2007

Keywords

Comments

Part of the phi_k family of sequences defined by a(1)=1, a(2)=...=a(k)=0, a(n)=a(n-k)+a(n-k+1) for n>k. phi_2 is a shift of the Fibonacci sequence and phi_3 is a shift of the Padovan sequence.

References

  • S. Suter, Binet-like formulas for recurrent sequences with characteristic equation x^k=x+1, preprint, 2007. [Apparently unpublished as of May 2016]

Programs

  • PARI
    Vec(x*(1-x)*(1+x+x^2+x^3+x^4)/(1-x^5-x^6) + O(x^100)) \\ Colin Barker, May 30 2016

Formula

Binet-like formula: a(n) = Sum_{i=1..6} (r_i^n)/(5(r_i)^2+6(r_i)) where r_i is a root of x^6=x+1.
a(n) = A017837(n-6). - R. J. Mathar, Sep 20 2012
G.f.: x*(1-x)*(1+x+x^2+x^3+x^4) / (1-x^5-x^6). - Colin Barker, May 30 2016
Showing 1-10 of 10 results.