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.

Previous Showing 11-20 of 31 results. Next

A132684 a(n) = binomial(2^n + n + 1, n).

Original entry on oeis.org

1, 4, 21, 220, 5985, 501942, 143218999, 145944307080, 542150225230185, 7398714129087308170, 372134605932348010322571, 69146263065062394421802892300, 47589861944854471977019273909187085
Offset: 0

Views

Author

Paul D. Hanna, Aug 26 2007

Keywords

Examples

			From _Paul D. Hanna_, Feb 25 2009: (Start)
G.f.: A(x) = 1 + 4*x + 21*x^2 + 220*x^3 + 5985*x^4 + 501942*x^5 +...
A(x) = 1/(1-x)^2 - log(1-2x)/(1-2x)^2 + log(1-4x)^2/((1-4x)^2*2!) - log(1-8x)^3/((1-8x)^2*3!) +- ... (End)
		

Crossrefs

Sequences of the form binomial(2^n +p*n +q, n): A136556 (0,-1), A014070 (0,0), A136505 (0,1), A136506 (0,2), A060690 (1,-1), A132683 (1,0), this sequence (1,1), A132685 (2,0), A132686 (2,1), A132687 (3,-1), A132688 (3,0), A132689 (3,1).
Cf. A136555.
Cf. A066384. - Paul D. Hanna, Feb 25 2009

Programs

  • Magma
    [Binomial(2^n +n+1, n): n in [0..20]]; // G. C. Greubel, Mar 14 2021
  • Maple
    A132684:= n-> binomial(2^n +n+1, n); seq(A132684(n), n=0..20); # G. C. Greubel, Mar 14 2021
  • Mathematica
    Table[Binomial[2^n+n+1,n],{n,0,20}] (* Harvey P. Dale, Nov 10 2011 *)
  • PARI
    a(n)=binomial(2^n+n+1,n)
    
  • PARI
    {a(n)=polcoeff(sum(m=0,n,(-log(1-2^m*x))^m/((1-2^m*x +x*O(x^n))^2*m!)),n)} \\ Paul D. Hanna, Feb 25 2009
    
  • Sage
    [binomial(2^n +n+1, n) for n in (0..20)] # G. C. Greubel, Mar 14 2021
    

Formula

a(n) = [x^n] 1/(1-x)^(2^n + 2).
G.f.: Sum_{n>=0} (-log(1 - 2^n*x))^n / ((1 - 2^n*x)^2*n!). - Paul D. Hanna, Feb 25 2009
a(n) ~ 2^(n^2) / n!. - Vaclav Kotesovec, Jul 02 2016

A132685 a(n) = binomial(2^n + 2*n, n).

Original entry on oeis.org

1, 4, 28, 364, 10626, 850668, 218618940, 198773423848, 669741609663270, 8493008777332033900, 405943250253048290447028, 72938914603968404495709630360, 49143490709866058459392200362497820
Offset: 0

Views

Author

Paul D. Hanna, Aug 26 2007

Keywords

Crossrefs

Sequences of the form binomial(2^n +p*n +q, n): A136556 (0,-1), A014070 (0,0), A136505 (0,1), A136506 (0,2), A060690 (1,-1), A132683 (1,0), A132684 (1,1), this sequence (2,0), A132686 (2,1), A132687 (3,-1), A132688 (3,0), A132689 (3,1).
Cf. A136555.

Programs

  • Magma
    [Binomial(2^n+2*n,n): n in [0..20]]; // G. C. Greubel, Mar 14 2021
  • Maple
    A132695:= n-> binomial(2^n +2*n,n); seq(A132685(n), n=0..20); # G. C. Greubel, Mar 14 2021
  • Mathematica
    Table[Binomial[2^n+2n,n],{n,0,20}] (* Harvey P. Dale, Jun 01 2016 *)
  • PARI
    a(n)=binomial(2^n+2*n,n)
    
  • Sage
    [binomial(2^n+2*n,n) for n in (0..20)] # G. C. Greubel, Mar 14 2021
    

Formula

a(n) = [x^n] 1/(1-x)^(2^n + n + 1).

A132686 a(n) = binomial(2^n + 2*n + 1, n).

Original entry on oeis.org

1, 5, 36, 455, 12650, 962598, 237093780, 209004408899, 689960224294614, 8639439963148103450, 409865407260324119340236, 73328394245057556170201283726, 49287010273876375495535472789937580
Offset: 0

Views

Author

Paul D. Hanna, Aug 26 2007

Keywords

Crossrefs

Sequences of the form binomial(2^n +p*n +q, n): A136556 (0,-1), A014070 (0,0), A136505 (0,1), A136506 (0,2), A060690 (1,-1), A132683 (1,0), A132684 (1,1), A132685 (2,0), this sequence (2,1), A132687 (3,-1), A132688 (3,0), A132689 (3,1).
Cf. A136555.

Programs

  • Magma
    [Binomial(2^n +2*n +1, n): n in [0..20]]; // G. C. Greubel, Mar 13 2021
  • Mathematica
    Table[Binomial[2^n +2*n +1, n], {n,0,20}] (* G. C. Greubel, Mar 13 2021 *)
  • PARI
    a(n)=binomial(2^n+2*n+1,n)
    
  • Sage
    [binomial(2^n +2*n +1, n) for n in (0..20)] # G. C. Greubel, Mar 13 2021
    

Formula

a(n) = [x^n] 1/(1-x)^(2^n + n + 2).

A132687 a(n) = binomial(2^n + 3*n - 1, n).

Original entry on oeis.org

1, 4, 36, 560, 17550, 1370754, 324540216, 267212177232, 822871715492970, 9728874233306696390, 442491588454024774291770, 76919746769405407508866898400, 50743487119356450255156023756871000
Offset: 0

Views

Author

Paul D. Hanna, Aug 26 2007

Keywords

Crossrefs

Sequences of the form binomial(2^n +p*n +q, n): A136556 (0,-1), A014070 (0,0), A136505 (0,1), A136506 (0,2), A060690 (1,-1), A132683 (1,0), A132684 (1,1), A132685 (2,0), A132686 (2,1), this sequence (3,-1), A132688 (3,0), A132689 (3,1).
Cf. A136555.

Programs

  • Magma
    [Binomial(2^n +3*n -1, n): n in [0..20]]; // G. C. Greubel, Mar 13 2021
  • Mathematica
    Table[Binomial[2^n+3n-1,n],{n,0,20}] (* Harvey P. Dale, Sep 07 2017 *)
  • PARI
    a(n)=binomial(2^n+3*n-1,n)
    
  • Sage
    [binomial(2^n +3*n -1, n) for n in (0..20)] # G. C. Greubel, Mar 13 2021
    

Formula

a(n) = [x^n] 1/(1-x)^(2^n + 2*n).

A132688 a(n) = binomial(2^n + 3*n, n).

Original entry on oeis.org

1, 5, 45, 680, 20475, 1533939, 350161812, 280384608504, 847073824772175, 9894081531608130857, 446730013630787463700695, 77328499046923986969058944720, 50891283683781760304442885961988100
Offset: 0

Views

Author

Paul D. Hanna, Aug 26 2007

Keywords

Crossrefs

Sequences of the form binomial(2^n +p*n +q, n): A136556 (0,-1), A014070 (0,0), A136505 (0,1), A136506 (0,2), A060690 (1,-1), A132683 (1,0), A132684 (1,1), A132685 (2,0), A132686 (2,1), A132687 (3,-1), this sequence (3,0), A132689 (3,1).
Cf. A136555.

Programs

  • Magma
    [Binomial(2^n +3*n, n): n in [0..20]]; // G. C. Greubel, Mar 13 2021
  • Mathematica
    Table[Binomial[2^n+3n,n],{n,0,20}] (* Harvey P. Dale, Oct 30 2018 *)
  • PARI
    a(n)=binomial(2^n+3*n,n)
    
  • Sage
    [binomial(2^n +3*n, n) for n in (0..20)] # G. C. Greubel, Mar 13 2021
    

Formula

a(n) = [x^n] 1/(1-x)^(2^n + 2*n + 1).

A132689 a(n) = binomial(2^n + 3*n + 1, n).

Original entry on oeis.org

1, 6, 55, 816, 23751, 1712304, 377447148, 294109729200, 871896500955975, 10061777828754031380, 451004941990890693018405, 77739225019650285306412710240, 51039474754930845750609669420261300
Offset: 0

Views

Author

Paul D. Hanna, Aug 26 2007

Keywords

Crossrefs

Sequences of the form binomial(2^n +p*n +q, n): A136556 (0,-1), A014070 (0,0), A136505 (0,1), A136506 (0,2), A060690 (1,-1), A132683 (1,0), A132684 (1,1), A132685 (2,0), A132686 (2,1), A132687 (3,-1), A132688 (3,0), this sequence (3,1).
Cf. A136555.

Programs

  • Magma
    [Binomial(2^n+3*n+1, n) : n in [0..15]]; // Wesley Ivan Hurt, Nov 20 2014
    
  • Maple
    A132689:=n->binomial(2^n+3*n+1, n): seq(A132689(n), n=0..15); # Wesley Ivan Hurt, Nov 20 2014
  • Mathematica
    Table[Binomial[2^n +3n +1, n], {n, 0, 15}] (* Wesley Ivan Hurt, Nov 20 2014 *)
  • PARI
    a(n)=binomial(2^n+3*n+1,n)
    
  • Sage
    [binomial(2^n +3*n+1, n) for n in (0..15)] # G. C. Greubel, Feb 15 2021

Formula

a(n) = [x^n] 1/(1-x)^(2^n + 2*n + 2).

A086675 Number of n X n (0,1)-matrices modulo cyclic permutations of the rows.

Original entry on oeis.org

1, 2, 10, 176, 16456, 6710912, 11453291200, 80421421917440, 2305843009750581376, 268650182136584290872320, 126765060022823052739661424640, 241677817415439249618874010960064512, 1858395433210885261795036719974526548094976
Offset: 0

Views

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Jul 27 2003

Keywords

Comments

Also the number of digraphical necklaces with n vertices. A digraphical necklace is defined to be a directed graph that is minimal among all n rotations of the vertices. Alternatively, it is an equivalence class of directed graphs under rotation of the vertices. These are a kind of partially labeled digraphs. - Gus Wiseman, Mar 04 2019

Examples

			From _Gus Wiseman_, Mar 04 2019: (Start)
Inequivalent representatives of the a(2) = 10 digraphical necklace edge-sets:
  {}
  {(1,1)}
  {(1,2)}
  {(1,1),(1,2)}
  {(1,1),(2,1)}
  {(1,1),(2,2)}
  {(1,2),(2,1)}
  {(1,1),(1,2),(2,1)}
  {(1,1),(1,2),(2,2)}
  {(1,1),(1,2),(2,1),(2,2)}
(End)
		

Crossrefs

Cf. A000031 (binary necklaces), A000939 (cycle necklaces), A008965, A060690, A061417 (permutation necklaces), A184271, A192332 (graphical necklaces), A275527 (path necklaces), A323858 (toroidal necklaces), A323870.

Programs

  • Mathematica
    Table[Fold[ #1+EulerPhi[ #2] 2^(n^2 /#2)&, 0, Divisors[n]]/n, {n, 16}]
    (* second program *)
    rotdigra[g_,m_]:=Sort[g/.k_Integer:>If[k==m,1,k+1]];
    Table[Length[Select[Subsets[Tuples[Range[n],2]],#=={}||#==First[Sort[Table[Nest[rotdigra[#,n]&,#,j],{j,n}]]]&]],{n,0,4}] (* Gus Wiseman, Mar 04 2019 *)

Formula

a(n) = (1/n)*Sum_{ d divides n } phi(d)*2^(n^2/d) for n > 0, a(0) = 1.

Extensions

More terms from Wouter Meeussen, Jul 29 2003
a(0)=1 prepended by Gus Wiseman, Mar 04 2019

A137153 Triangle, read by rows, where T(n,k) = C(2^k + n-k-1, n-k).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 4, 1, 1, 4, 10, 8, 1, 1, 5, 20, 36, 16, 1, 1, 6, 35, 120, 136, 32, 1, 1, 7, 56, 330, 816, 528, 64, 1, 1, 8, 84, 792, 3876, 5984, 2080, 128, 1, 1, 9, 120, 1716, 15504, 52360, 45760, 8256, 256, 1, 1, 10, 165, 3432, 54264, 376992, 766480, 357760, 32896
Offset: 0

Views

Author

Paul D. Hanna, Jan 24 2008

Keywords

Comments

Matrix inverse is A137156.
T(n,k) is the number of relations between a set of k distinguishable elements and a set of n-k indistinguishable elements. - Isaac R. Browne, Jun 04 2025

Examples

			Triangle begins:
  1;
  1,  1;
  1,  2,   1;
  1,  3,   4,    1;
  1,  4,  10,    8,     1;
  1,  5,  20,   36,    16,      1;
  1,  6,  35,  120,   136,     32,      1;
  1,  7,  56,  330,   816,    528,     64,      1;
  1,  8,  84,  792,  3876,   5984,   2080,    128,     1;
  1,  9, 120, 1716, 15504,  52360,  45760,   8256,   256,   1;
  1, 10, 165, 3432, 54264, 376992, 766480, 357760, 32896, 512, 1;
  ...
		

Crossrefs

Cf. A137154 (row sums), A137155 (antidiagonal sums), A060690 (central terms); A137156 (matrix inverse).
Cf. A092056 (same with reflected rows).

Programs

  • Mathematica
    Table[Binomial[2^k+n-k-1,n-k],{n,0,10},{k,0,n}]//Flatten (* Harvey P. Dale, Mar 06 2017 *)
  • PARI
    {T(n,k)=binomial(2^k+n-k-1,n-k)}
    for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))
    
  • PARI
    {T(n, k) = polcoeff(1/(1-x+x*O(x^n))^(2^k), n-k)}
    for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))

A089006 Number of distinct n X n (0,1) matrices after double sorting: by row, by column, by row .. until reaching a fixed point.

Original entry on oeis.org

1, 2, 7, 45, 650, 24520, 2625117, 836488618, 818230288201, 2513135860300849, 24686082394548211147, 787959836124458000837941, 82905574521614049485027140026
Offset: 0

Views

Author

Wouter Meeussen, Nov 03 2003

Keywords

Comments

Also, number of n X n binary matrices with both rows and columns, considered as binary numbers, in nondecreasing order. (Ordering only rows gives A060690.) - R. H. Hardin, May 08 2008
A result of Adolf Mader and Otto Mutzbauer shows that the two definitions are equivalent. - Victor S. Miller, Feb 03 2009
For n=5, only 0.07% remain distinct. Sorting columns and\or rows does not change the permanent of the matrix and leaves the absolute value of the determinant unchanged.
Diagonal of A180985.

Examples

			The 7 (2 X 2)-matrices are {{0,0},{0,0}}, {{0,0},{0,1}}, {{0,0},{1,1}}, {{0,1},{0,1}}, {{0,1},{1,0}}, {{0,1},{1,1}} and {{1,1},{1,1}}.
		

References

  • Adolf Mader and Otto Mutzbauer, "Double Orderings of (0,1) Matrices", Ars Combinatoria v. 61 (2001) pp 81-95.

Crossrefs

Column 0 of A374525.

Programs

  • Mathematica
    baseform[li_List] := FixedPoint[Sort[Transpose[Sort[Transpose[Sort[ #1]]]]]&, li]; Table[Length@Split[Sort[baseform/@(Partition[ #, n]&/@(IntegerDigits[Range[0, -1+2^n^2], 2, n^2]))]], {n, 4}]

Extensions

a(6)-a(12) found by R. H. Hardin, May 08 2008. These terms were found using bdd's (binary decision diagrams), just setting up the logical relations between bits in a gigantic bdd expression and using that to count the satisfying states.
Edited by N. J. A. Sloane, Feb 05 2009 at the suggestion of Victor S. Miller

A092056 Square table read by downward antidiagonals where T(n,k) = binomial(n+2^k-1,n).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 3, 1, 1, 8, 10, 4, 1, 1, 16, 36, 20, 5, 1, 1, 32, 136, 120, 35, 6, 1, 1, 64, 528, 816, 330, 56, 7, 1, 1, 128, 2080, 5984, 3876, 792, 84, 8, 1, 1, 256, 8256, 45760, 52360, 15504, 1716, 120, 9, 1, 1, 512, 32896, 357760, 766480, 376992, 54264, 3432, 165, 10, 1
Offset: 0

Views

Author

Henry Bottomley, Feb 19 2004

Keywords

Comments

Each column is convolution of preceding column starting from the all 1's sequence.
T(n,k) is the number of relations between a set of k distinguishable elements and a set of n indistinguishable elements. - Isaac R. Browne, May 14 2025

Examples

			Rows start:
  1, 1,  1,   1,    1,     1,      1,...
  1, 2,  4,   8,   16,    32,     64,...
  1, 3, 10,  36,  136,   528,   2080,...
  1, 4, 20, 120,  816,  5984,  45760,...
  1, 5, 35, 330, 3876, 52360, 766480,...
  ...
		

Crossrefs

Columns include (essentially) A000012, A000027, A000292, A000580, A010968, etc.
Rows include A000012, A000079, A007582, A092056.
Main diagonal gives A060690.
Cf. A137153 (same with reflected antidiagonals).

Formula

T(n,k) = Sum_{i=0..n} T(i,k-1)*T(n-i,k-1) starting with T(n,0) = 1 for n>=0.
Previous Showing 11-20 of 31 results. Next