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.

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A099099 Quadrisection of a generalized Padovan sequence.

Original entry on oeis.org

1, 1, 1, 2, 6, 16, 37, 80, 172, 377, 839, 1874, 4175, 9274, 20577, 45665, 101393, 225193, 500162, 1110790, 2466760, 5477917, 12164896, 27015092, 59993817, 133231279, 295872778, 657057431, 1459155634, 3240410561, 7196122817
Offset: 0

Views

Author

Paul Barry, Sep 29 2004

Keywords

Comments

Quadrisection of sequence with g.f. 1/(1 - x^3 - x^4), or A017817.

Programs

Formula

G.f.: (1-x)^3/((1-x)^4-x^3).
a(n) = sum_{k=0..2n} binomial(k, 4n-3k).
a(n) = 4a(n-1) - 6a(n-2) + 5a(n-3) - a(n-4).
a(n) = A017817(4n).
a(n) = sum_{k=0..floor((n+1)/2)} binomial(n+k, 4k). - Paul Barry, May 09 2005

A110064 a(n+4) = a(n+1) - a(n), a(0) = 1, a(1) = -4, a(2) = 0, a(3) = 1.

Original entry on oeis.org

1, -4, 0, 1, -5, 4, 1, -6, 9, -3, -7, 15, -12, -4, 22, -27, 8, 26, -49, 35, 18, -75, 84, -17, -93, 159, -101, -76, 252, -260, 25, 328, -512, 285, 303, -840, 797, 18, -1143, 1637, -779, -1161, 2780, -2416, -382, 3941, -5196, 2034, 4323, -9137, 7230, 2289, -13460, 16367, -4941, -15749, 29827, -21308, -10808
Offset: 0

Views

Author

Creighton Dement, Jul 10 2005

Keywords

Comments

One of several sequences, apparently all of the form a(n+4) = a(n+1) - a(n), which appear to "spiral outwards" when plotted against each other (see A110061-64). In reference to the FAMP program code, A017817 is also in this same batch of sequences and satisfies the same recurrence relation.

Crossrefs

Programs

  • Maple
    seriestolist(series(-(-1+4*x)/(1-x^3+x^4), x=0,60)); -or- Floretion Algebra Multiplication Program, FAMP Code: 4kbaseseq[A*B] with A = + .5'i + .5'j + .5'k + .5e and B = - .5'i - .25'j + .25'k - .5i' - .25j' + .25k' - .5'ii' - .25'ij' - .25'ik' - .25'ji' - .25'ki' - .5e
  • Mathematica
    LinearRecurrence[{0,0,1,-1},{1,-4,0,1},60] (* Harvey P. Dale, Oct 23 2016 *)

Formula

Expansion of (4*x-1)/(1-x^3+x^4)

A246690 Number A(n,k) of compositions of n into parts of the k-th list of distinct parts in the order given by A246688; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 2, 0, 1, 0, 1, 1, 0, 3, 1, 1, 0, 1, 0, 1, 1, 5, 0, 1, 0, 1, 1, 0, 2, 0, 8, 1, 1, 0, 1, 0, 1, 0, 3, 0, 13, 0, 1, 0, 1, 0, 1, 1, 1, 4, 1, 21, 1, 1, 0, 1, 1, 0, 1, 2, 0, 6, 0, 34, 0, 1, 0, 1, 1, 2, 0, 1, 3, 0, 9, 0, 55, 1, 1, 0
Offset: 0

Views

Author

Alois P. Heinz, Sep 01 2014

Keywords

Comments

The first lists of distinct parts in the order given by A246688 are: 0:[], 1:[1], 2:[2], 3:[1,2], 4:[3], 5:[1,3], 6:[4], 7:[1,4], 8:[2,3], 9:[5], 10:[1,2,3], 11:[1,5], 12:[2,4], 13:[6], 14:[1,2,4], 15:[1,6], 16:[2,5], 17:[3,4], 18:[7], 19:[1,2,5], 20:[1,3,4], ... .

Examples

			Square array A(n,k) begins:
  1, 1, 1,  1, 1,  1, 1,  1, 1, 1,   1, 1, 1, 1,   1, ...
  0, 1, 0,  1, 0,  1, 0,  1, 0, 0,   1, 1, 0, 0,   1, ...
  0, 1, 1,  2, 0,  1, 0,  1, 1, 0,   2, 1, 1, 0,   2, ...
  0, 1, 0,  3, 1,  2, 0,  1, 1, 0,   4, 1, 0, 0,   3, ...
  0, 1, 1,  5, 0,  3, 1,  2, 1, 0,   7, 1, 2, 0,   6, ...
  0, 1, 0,  8, 0,  4, 0,  3, 2, 1,  13, 2, 0, 0,  10, ...
  0, 1, 1, 13, 1,  6, 0,  4, 2, 0,  24, 3, 3, 1,  18, ...
  0, 1, 0, 21, 0,  9, 0,  5, 3, 0,  44, 4, 0, 0,  31, ...
  0, 1, 1, 34, 0, 13, 1,  7, 4, 0,  81, 5, 5, 0,  55, ...
  0, 1, 0, 55, 1, 19, 0, 10, 5, 0, 149, 6, 0, 0,  96, ...
  0, 1, 1, 89, 0, 28, 0, 14, 7, 1, 274, 8, 8, 0, 169, ...
		

Crossrefs

Main diagonal gives A246691.
Cf. A246688, A246720 (the same for partitions).

Programs

  • Maple
    b:= proc(n, i) b(n, i):= `if`(n=0, [[]], `if`(i>n, [],
          [map(x->[i, x[]], b(n-i, i+1))[], b(n, i+1)[]]))
        end:
    f:= proc() local i, l; i, l:=0, [];
          proc(n) while n>=nops(l)
            do l:=[l[], b(i, 1)[]]; i:=i+1 od; l[n+1]
          end
        end():
    g:= proc(n, l) option remember; `if`(n=0, 1,
          add(`if`(i>n, 0, g(n-i, l)), i=l))
        end:
    A:= (n, k)-> g(n, f(k)):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, {{}}, If[i>n, {}, Join[Prepend[#, i]& /@ b[n - i, i + 1], b[n, i + 1]]]];
    f = Module[{i = 0, l = {}}, Function[n, While[n >= Length[l], l = Join[l, b[i, 1]]; i++]; l[[n + 1]]]];
    g[n_, l_] := g[n, l] = If[n==0, 1, Sum[If[i>n, 0, g[n - i, l]], {i, l}]];
    A[n_, k_] := g[n, f[k]];
    Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Dec 07 2020, after Alois P. Heinz *)

A123552 Expansion of 1/(1 - x - x^3 + x^5).

Original entry on oeis.org

1, 1, 1, 2, 3, 3, 4, 6, 7, 8, 11, 14, 16, 20, 26, 31, 37, 47, 58, 69, 85, 106, 128, 155, 192, 235, 284, 348, 428, 520, 633, 777, 949, 1154, 1411, 1727, 2104, 2566, 3139, 3832, 4671, 5706, 6972, 8504, 10378, 12679, 15477, 18883, 23058, 28157, 34361, 41942, 51216, 62519
Offset: 0

Views

Author

Christian G. Bower, Nov 14 2006

Keywords

Crossrefs

Number of nodes at n-th generation in A123015.

Programs

Formula

G.f.: 1/((1-x)*(1-x^3-x^4)).
From Robert FERREOL, Sep 12 2017: (Start)
a(n) = a(n-1) + a(n-3) - a(n-5) for n >= 5, with a(0)=a(1)=a(2)=1, a(3)=2, a(4)=3.
a(n) = a(n-3) + a(n-4) + 1 for n >= 4, with a(0)=a(1)=a(2)=1, a(3)=2.
a(n) - a(n-1) = A017817(n). (End)

A001584 A generalized Fibonacci sequence.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 4, 4, 4, 7, 7, 8, 12, 12, 16, 21, 21, 31, 37, 38, 58, 65, 71, 106, 114, 135, 191, 201, 257, 341, 359, 485, 605, 652, 904, 1070, 1202, 1664, 1894, 2237, 3029, 3370, 4176, 5464, 6048, 7779, 9793, 10963, 14411, 17492, 20054, 26507, 31239, 36924, 48396
Offset: 0

Views

Author

Keywords

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).

Crossrefs

Cf. A017817.

Programs

  • Maple
    A001584:=(z-1)*(z**2+z+1)**2/(z**4-z**3+1)/(z**4+z**3-1); # Simon Plouffe in his 1992 dissertation
  • PARI
    Vec((1+x+x^2-x^3-x^4-x^5)/(1-2*x^3+x^6-x^8) + O(x^80)) \\ Michel Marcus, Sep 07 2017

Formula

G.f.: (1 + x + x^2 - x^3 - x^4 - x^5)/(1 - 2*x^3 + x^6 - x^8).

Extensions

More terms from David W. Wilson

A052697 Expansion of e.g.f. 1/(1-x^3-x^4).

Original entry on oeis.org

1, 0, 0, 6, 24, 0, 720, 10080, 40320, 362880, 10886400, 119750400, 958003200, 24908083200, 523069747200, 6538371840000, 125536739328000, 3556874280960000, 70426110763008000, 1338096104497152000
Offset: 0

Views

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n)*(&+[Binomial(k,n-3*k): k in [0..Floor(n/3)]]): n in [0..30]]; // G. C. Greubel, May 31 2022
    
  • Maple
    spec := [S,{S=Sequence(Prod(Z,Z,Union(Z,Prod(Z,Z))))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
  • Mathematica
    With[{nn=20},CoefficientList[Series[1/(1-x^3-x^4),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Mar 06 2016 *)
  • SageMath
    [factorial(n)*sum(binomial(k, n-3*k) for k in (0..n//3)) for n in (0..30)] # G. C. Greubel, May 31 2022

Formula

E.g.f.: 1/(1 - x^3 - x^4).
D-finite recurrence: a(0)=1, a(1)=0, a(2)=0, a(3)=6, a(n+4) = (24 + 26*n + 9*n^2 + n^3)*a(n+1) + (24 + 50*n + 35*n^2 + 10*n^3 + n^4)*a(n).
a(n) = (n!/283) * Sum_{alpha=RootOf(-1 + Z^3 + Z^4)} (- 16 - 73*alpha + 3*alpha^2 + 12*alpha^3)*alpha^(-1-n).
a(n) = n!*A017817(n). - R. J. Mathar, Nov 27 2011

A127838 a(1) = 1, a(2) = a(3) = a(4) = 0; a(n) = a(n-4) + a(n-3) for n > 4.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 2, 1, 1, 3, 3, 2, 4, 6, 5, 6, 10, 11, 11, 16, 21, 22, 27, 37, 43, 49, 64, 80, 92, 113, 144, 172, 205, 257, 316, 377, 462, 573, 693, 839, 1035, 1266, 1532, 1874, 2301, 2798, 3406, 4175, 5099, 6204, 7581
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.
The sequence can be interpreted as the top-left element of the n-th power of 6 different 4 X 4 (0,1) matrices. - R. J. Mathar, Mar 19 2014

References

  • G. Mantel, Resten van wederkeerige Reeksen (Remainders of the reciprocal series), Nieuw Archief v. Wiskunde, 2nd series, I (1894), 172-184. [From N. J. A. Sloane, Dec 17 2010]
  • S. Suter, Binet-like formulas for recurrent sequences with characteristic equation x^k=x+1, preprint, 2007, apparently unpublished as of Mar 2014.

Programs

  • Mathematica
    LinearRecurrence[{0,0,1,1},{1,0,0,0},60] (* Harvey P. Dale, Feb 15 2015 *)

Formula

Binet-like formula: a(n) = Sum_{i=1...4} (r_i^n)/(3(r_i)^2+4(r_i)) where r_i is a root of x^4=x+1.
From R. J. Mathar, Mar 06 2008: (Start)
a(n) = A017817(n-5) for n >= 5.
O.g.f.: x(x-1)(1+x+x^2)/(x^4+x^3-1). (End)

A243254 Number of compositions of n into parts {3,4,5} when all parts 3,4 and 5 are present.

Original entry on oeis.org

6, 0, 0, 12, 12, 12, 20, 30, 50, 60, 80, 120, 162, 225, 305, 401, 560, 763, 1017, 1365, 1834, 2484, 3328, 4420, 5936, 7943, 10593, 14148, 18828, 25092, 33468, 44517, 59214, 78734, 104698, 139232, 184889, 245532, 326177, 433052, 574841, 762856, 1012219, 1343160
Offset: 12

Views

Author

David Neil McGrath, Jul 30 2014

Keywords

Comments

Compositions of n from the set {3,4,5} that can be partitioned into the equivalence classes [345][34][45][35][3][4][5], where each class is defined by the relation "all elements are present".

Examples

			a(24) = 162 = 42 + 90 + 30: the tuples are (5433333) -> 7!/5! = 42, (554433) -> 6!/2!2!2! = 90, (544443) -> 6!/4! = 30.
		

Crossrefs

Programs

  • Maple
    N:= 100;
    C34:= Vector(N):
    C35:= Vector(N):
    C45:= Vector(N):
    C345:= Vector(N):
    C1:= Vector(N,i -> numboccur([i mod 3, i mod 4, i mod 5],0)):
    C34[3]:= 1: C34[4]:= 1:
    C35[3]:= 1: C35[5]:= 1:
    C45[4]:= 1: C45[5]:= 1:
    C345[3]:= 1: C345[4]:= 1: C345[5]:= 1:
    for n from 6 to N do
      C34[n]:= C34[n-3] + C34[n-4];
      C35[n]:= C35[n-3] + C35[n-5];
      C45[n]:= C45[n-4] + C45[n-5];
      C345[n]:= C345[n-3]+C345[n-4]+C345[n-5];
    od:
    A:= C345 - C34 - C35 - C45 + C1:
    convert(A[12..N],list); # Robert Israel, Aug 18 2014
  • Mathematica
    CoefficientList[Series[x^12*(x^15 + 5*x^14 + 13*x^13 + 24*x^12 + 34*x^11 + 36*x^10 + 24*x^9 - 26*x^7 - 40*x^6 - 36*x^5 - 18*x^4 + 12*x^2 + 12*x +6)/((1 - x)*(x + 1)*(x^2 + 1)*(x^3 + x^2 - 1)*(x^4 + x^3 - 1)*(x^5 + x^3 - 1)*(x^2 + x + 1)*(x^5 + x^4 - 1)*(x^4 + x^3 + x^2 + x + 1)), {x, 0, 50}], x] (* Wesley Ivan Hurt, Aug 02 2014 *)
    Drop[LinearRecurrence[{-2,-2,2,9,16,14,-2,-29,-52,-52,-20,34,82,97,67,7,-53,-84,-77,-43,-4,22,29,23,13,5,1},{0,0,0,0,0,0,0,0,0,0,0,0,6,0,0,12,12,12,20,30,50,60,80,120,162,225,305,401},60],12] (* Harvey P. Dale, Jun 06 2025 *)

Formula

a(n) = A017818(n-1) -A245492(n) -A245487(n) -A245527(n) -A022003(n) -A011765(n) -A112765(n).
G.f.: -(x^15 +5*x^14 +13*x^13 +24*x^12 +34*x^11 +36*x^10 +24*x^9-26*x^7 -40*x^6 -36*x^5 -18*x^4 +12*x^2 +12*x +6) *x^12 /((x-1) *(x+1) *(x^2+1) *(x^3+x^2-1) *(x^4+x^3-1) *(x^5+x^3-1) *(x^2+x+1) *(x^5+x^4-1) *(x^4+x^3+x^2+x+1)). - Alois P. Heinz, Jul 30 2014
a(n) = A017818(n) - A017817(n) - A052920(n) - A017827(n) + A079978(n) + A121262(n) + A079998(n). - Robert Israel, Aug 18 2014

A373742 Expansion of e.g.f. exp(x^3/6 * (1 + x)).

Original entry on oeis.org

1, 0, 0, 1, 4, 0, 10, 140, 560, 280, 8400, 92400, 385000, 800800, 16816800, 169569400, 784784000, 3811808000, 68803134400, 673546473600, 3693641952000, 30454440016000, 507477434464000, 5002277568288000, 33870732912016000, 386622918281600000
Offset: 0

Views

Author

Seiichi Manyama, Jun 16 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*sum(k=0, n\3, binomial(k, n-3*k)/(6^k*k!));

Formula

a(n) = n! * Sum_{k=0..floor(n/3)} binomial(k,n-3*k)/(6^k * k!).
a(n) = (n-1)*(n-2)/6 * (3*a(n-3) + 4*(n-3)*a(n-4)).

A099101 Quintisection of 1/(1-x^3-x^4).

Original entry on oeis.org

1, 0, 3, 5, 16, 43, 113, 316, 839, 2301, 6204, 16855, 45665, 123800, 335659, 909845, 2466760, 6686979, 18128529, 49145300, 133231279, 361184653, 979156724, 2654456239, 7196122817, 19508406192, 52886508243, 143373224101
Offset: 0

Views

Author

Paul Barry, Sep 29 2004

Keywords

Crossrefs

Cf. A099099.

Formula

a(n)=sum{k=0..floor(5n/3), binomial(k, 5n-3k)}.
a(n)=A017817(5n).
G.f.: (1+x)*(x^2+x-1) / ( -1+5*x^2+6*x^3+x^4 ). - R. J. Mathar, Feb 19 2015
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