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 11-19 of 19 results.

A216357 Expansion of 1/( (1-16*x)*(1+4*x)^2 )^(1/4).

Original entry on oeis.org

1, 2, 38, 404, 5510, 74492, 1048924, 15004776, 217943238, 3200089580, 47405806708, 707305846936, 10616181542044, 160142807848792, 2426097698458360, 36890818642990544, 562772826273060678, 8609639617006367052, 132048790603779592196, 2029851945081220214200
Offset: 0

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Author

Paul D. Hanna, Sep 04 2012

Keywords

Examples

			G.f.: A(x) = 1 + 2*x + 38*x^2 + 404*x^3 + 5510*x^4 + 74492*x^5 + 1048924*x^6 + ...
where 1/A(x)^4 = 1 - 8*x - 112*x^2 - 256*x^3.
The logarithm of the g.f. begins:
log(A(x)) = x + 2*x^2/2 + 72*x^3/3 + 992*x^4/4 + 16512*x^5/5 + 261632*x^6/6 + 4196352*x^7/7 + ... + A070775(n)*x^n/n + ...
		

Crossrefs

Programs

  • Maple
    f:= gfun:-rectoproc({(48+64*n)*a(n)+(14+12*n)*a(n+1)+(-n-2)*a(n+2), a(0) = 1, a(1) = 2}, a(n), remember):
    map(f, [$0..30]); # Robert Israel, Dec 09 2016
  • Mathematica
    a = DifferenceRoot[Function[{a, n}, {(48+64n) a[n] + (14+12n) a[1+n] + (-2-n) a[2+n] == 0, a[0] == 1, a[1] == 2}]];
    Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Sep 16 2022, after Robert Israel *)
  • PARI
    {a(n)=local(A=1+x); for(i=1, n, A=exp(sum(m=1, n, sum(j=0, m, binomial(4*m, 4*j))*x^m/m+x*O(x^n)))); polcoeff(A, n)}
    for(n=0, 31, print1(a(n), ", "))

Formula

G.f.: exp(Sum_{n>=1} A070775(n)*x^n/n) where A070775(n) = Sum_{k=0..n} binomial(4*n,4*k).
a(n) ~ GAMMA(3/4) * 2^(4*n+1/2) / (Pi* sqrt(5) * n^(3/4)). - Vaclav Kotesovec, Jul 31 2014
a(n) = ((64*n-80)*a(n-2)+(12*n-10)*a(n-1))/n. - Robert Israel, Dec 09 2016

A361043 Array read by descending antidiagonals. A(n, k) is, if n > 0, the number of multiset permutations of {0, 1} of length n * k where the number of occurrences of 1 are multiples of n. A(0, k) = k + 1.

Original entry on oeis.org

1, 2, 1, 3, 2, 1, 4, 4, 2, 1, 5, 8, 8, 2, 1, 6, 16, 32, 22, 2, 1, 7, 32, 128, 170, 72, 2, 1, 8, 64, 512, 1366, 992, 254, 2, 1, 9, 128, 2048, 10922, 16512, 6008, 926, 2, 1, 10, 256, 8192, 87382, 261632, 215766, 37130, 3434, 2, 1, 11, 512, 32768, 699050, 4196352, 6643782, 2973350, 232562, 12872, 2, 1
Offset: 0

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Author

Peter Luschny, Mar 18 2023

Keywords

Comments

Because of the interchangeability of 0 and 1 in the definition, A(n, k) is even if n, k >= 1. In other words, if the binary representation of a permutation of the defined type is counted, then so is the 1's complement of that representation.

Examples

			Array A(n, k) starts:
 [0] 1, 2,    3,      4,        5,          6,            7, ...  A000027
 [1] 1, 2,    4,      8,       16,         32,           64, ...  A000079
 [2] 1, 2,    8,     32,      128,        512,         2048, ...  A081294
 [3] 1, 2,   22,    170,     1366,      10922,        87382, ...  A007613
 [4] 1, 2,   72,    992,    16512,     261632,      4196352, ...  A070775
 [5] 1, 2,  254,   6008,   215766,    6643782,    215492564, ...  A070782
 [6] 1, 2,  926,  37130,  2973350,  174174002,  11582386286, ...  A070967
 [7] 1, 2, 3434, 232562, 42484682, 4653367842, 644032289258, ...  A094211
.
Triangle T(n, k) starts:
 [0]  1;
 [1]  2,   1;
 [2]  3,   2,    1;
 [3]  4,   4,    2,     1;
 [4]  5,   8,    8,     2,      1;
 [5]  6,  16,   32,    22,      2,      1;
 [6]  7,  32,  128,   170,     72,      2,     1;
 [7]  8,  64,  512,  1366,    992,    254,     2,    1;
 [8]  9, 128, 2048, 10922,  16512,   6008,   926,    2, 1;
 [9] 10, 256, 8192, 87382, 261632, 215766, 37130, 3434, 2, 1;
.
A(2, 2) = 8 = card(0000, 1100, 1010, 1001, 0110, 0101, 0011, 1111).
A(1, 3) = 8 = card(000, 100, 010, 001, 110, 101, 011, 111).
		

Crossrefs

Rows: A000027 (n=0), A000079 (n=1), A081294 (n=2), A007613 (n=3), A070775 (n=4), A070782 (n=5), A070967 (n=6), A094211 (n=7), A070832 (n=8), A094213 (n=9), A070833 (n=10).
Variant: A308500 (upwards antidiagonals).
Cf. A167009 (main diagonal).

Programs

  • Maple
    T := (n, k) -> add(binomial((n - k)*k, j*k), j = 0 .. n-k):
    seq(print(seq(T(n, k), k = 0..n)), n = 0..7);
  • SageMath
    # In Python use this import:
    # from sympy.utilities.iterables import multiset_permutations
    def A(n: int, k: int) -> int:
        if n == 0: return k + 1
        count = 0
        for a in range(0, n * k + 1, n):
            S = [i < a for i in range(n * k)]
            count += Permutations(S).cardinality()
        return count
    def ARow(n: int, size: int) -> list[int]:
        return [A(n, k) for k in range(size)]
    for n in range(6): print(ARow(n, 5))

Formula

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

A377855 Cogrowth sequence of the 16-element group C4:C4 = .

Original entry on oeis.org

1, 0, 2, 6, 40, 120, 512, 2016, 8320, 32640, 131072, 523776, 2099200, 8386560, 33554432, 134209536, 536903680, 2147450880, 8589934592, 34359607296, 137439477760, 549755289600, 2199023255552, 8796090925056, 35184380477440, 140737479966720, 562949953421312
Offset: 0

Views

Author

Sean A. Irvine, Nov 09 2024

Keywords

Comments

Gives the even terms, all the odd terms are 0.

Crossrefs

Cf. A070775 (C4 X C4), A377840 (C8 X C2).

Formula

G.f.: (12*x^4+6*x^3+2*x^2+2*x-1) / ((4*x-1) * (2*x+1) * (4*x^2+1)).

A308500 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals: A(n,k) = Sum_{j=0..n} binomial(k*n,k*j).

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 1, 2, 4, 4, 1, 2, 8, 8, 5, 1, 2, 22, 32, 16, 6, 1, 2, 72, 170, 128, 32, 7, 1, 2, 254, 992, 1366, 512, 64, 8, 1, 2, 926, 6008, 16512, 10922, 2048, 128, 9, 1, 2, 3434, 37130, 215766, 261632, 87382, 8192, 256, 10, 1, 2, 12872, 232562, 2973350, 6643782, 4196352, 699050, 32768, 512, 11
Offset: 0

Views

Author

Seiichi Manyama, Jun 01 2019

Keywords

Examples

			Square array begins:
   1,  1,    1,     1,       1,         1, ...
   2,  2,    2,     2,       2,         2, ...
   3,  4,    8,    22,      72,       254, ...
   4,  8,   32,   170,     992,      6008, ...
   5, 16,  128,  1366,   16512,    215766, ...
   6, 32,  512, 10922,  261632,   6643782, ...
   7, 64, 2048, 87382, 4196352, 215492564, ...
		

Crossrefs

Main diagonal gives A167009.

Programs

  • Mathematica
    T[n_, k_] := Sum[Binomial[k*n, k*j], {j, 0, n}] ; Table[T[k, n - k], {n, 0, 10}, {k, 0, n}] // Flatten (* Amiram Eldar, May 12 2021 *)

A177809 Symmetrical sequence:Binomial(n,5*m).

Original entry on oeis.org

1, 1, 1, 1, 252, 1, 1, 3003, 3003, 1, 1, 15504, 184756, 15504, 1, 1, 53130, 3268760, 3268760, 53130, 1, 1, 142506, 30045015, 155117520, 30045015, 142506, 1, 1, 324632, 183579396, 3247943160, 3247943160, 183579396, 324632, 1, 1, 658008, 847660528, 40225345056
Offset: 0

Views

Author

Roger L. Bagula, Dec 13 2010

Keywords

Comments

Row sums are A070782.
5th in the sequence of sequence Binomial(n,k*m),k=1,2,3,4,5,...

Examples

			{1},
{1, 1},
{1, 252, 1},
{1, 3003, 3003, 1},
{1, 15504, 184756, 15504, 1},
{1, 53130, 3268760, 3268760, 53130, 1},
{1, 142506, 30045015, 155117520, 30045015, 142506, 1},
{1, 324632, 183579396, 3247943160, 3247943160, 183579396, 324632, 1},
{1, 658008, 847660528, 40225345056, 137846528820, 40225345056, 847660528, 658008, 1},
{1, 1221759, 3190187286, 344867425584, 3169870830126, 3169870830126, 344867425584, 3190187286, 1221759, 1},
{1, 2118760, 10272278170, 2250829575120, 47129212243960, 126410606437752, 47129212243960, 2250829575120, 10272278170, 2118760, 1}
		

Crossrefs

Programs

  • Mathematica
    t[n_, m_] = Binomial[n, 5*m];
    Table[Table[t[n, m], {m, 0, Floor[n/5]}], {n, 0, 50, 5}];
    Flatten[%]

A377843 Cogrowth sequence of the 16-element group C4 X C2 X C2 = .

Original entry on oeis.org

1, 2, 9, 62, 689, 7322, 69369, 616982, 5422049, 48197042, 433434729, 3913915502, 35311723409, 317999340362, 2860994944089, 25738114039622, 231602961592769, 2084457277181282, 18761300850805449, 168858054223133342, 1519730933499158129, 13677470410291063802
Offset: 0

Views

Author

Sean A. Irvine, Nov 09 2024

Keywords

Comments

Gives the even terms, all the odd terms are 0.

Examples

			a(2)=9 corresponds to the words SSSS, TTTT, UUUU, TTUU, TUUT, UUTT, TUTU, UTUT, UTTU.
		

Crossrefs

Cf. A070775 (C4 X C4), A377714 (C4 X C2), A377840 (C8 X C2), A007582 (D8).

Programs

  • Mathematica
    LinearRecurrence[{15,-78,210,79,-225},{1, 2, 9, 62, 689},22] (* James C. McMahon, Nov 10 2024 *)

Formula

G.f.: (38*x^4+127*x^3-57*x^2+13*x-1) / ((1-x) * (9*x-1) * (x+1) * (25*x^2-6*x+1)).
E.g.f.: (2*exp(3*x)*cos(4*x) + 5*cosh(x) + cosh(9*x) + sinh(x) + sinh(9*x))/8. - Stefano Spezia, Nov 10 2024

A377943 Cogrowth sequence of the 16-element Pauli group C4 o D4 = .

Original entry on oeis.org

1, 1, 11, 91, 821, 7381, 66431, 597871, 5380841, 48427561, 435848051, 3922632451, 35303692061, 317733228541, 2859599056871, 25736391511831, 231627523606481, 2084647712458321, 18761829412124891, 168856464709124011, 1519708182382116101, 13677373641439044901
Offset: 0

Views

Author

Sean A. Irvine, Nov 11 2024

Keywords

Comments

Gives the even terms, all the odd terms are 0.

Crossrefs

Cf. A070775 (C4 X C4), A377855 (C4:C4), A047854 (D4 X C2).

Formula

G.f.: (x^2-8*x+1) / ((x-1) * (9*x-1) * (x+1)).

A090411 Expansion of g.f. (1-x)/(1-16*x).

Original entry on oeis.org

1, 15, 240, 3840, 61440, 983040, 15728640, 251658240, 4026531840, 64424509440, 1030792151040, 16492674416640, 263882790666240, 4222124650659840, 67553994410557440, 1080863910568919040, 17293822569102704640, 276701161105643274240, 4427218577690292387840
Offset: 0

Views

Author

Paul Barry, Nov 30 2003

Keywords

Crossrefs

Programs

Formula

a(n) = 15*16^(n-1) + 0^n/16.
a(n) = Sum_{j=0..3, Sum_{k=0..n, C(4*n+j, 4*k)}}.
a(n) = (A070775(n) + A090407(n) + A001025(n) + A090408(n))/4.
From Elmo R. Oliveira, Mar 25 2025: (Start)
E.g.f.: (15*exp(16*x) + 1)/16.
a(n) = 16*a(n-1) for n > 1. (End)

A177810 Triangle binomial(6*n,6*m), 0 <= m <= n, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 924, 1, 1, 18564, 18564, 1, 1, 134596, 2704156, 134596, 1, 1, 593775, 86493225, 86493225, 593775, 1, 1, 1947792, 1251677700, 9075135300, 1251677700, 1947792, 1, 1, 5245786, 11058116888, 353697121050, 353697121050, 11058116888, 5245786, 1
Offset: 0

Views

Author

Roger L. Bagula, Dec 13 2010

Keywords

Comments

Row sums are A070967. k=6 in binomial(k*n,k*m) sequence similar to k=2 in A086645, k=4 in A070775,...

Examples

			1;
1, 1;
1, 924, 1;
1, 18564, 18564, 1;
1, 134596, 2704156, 134596, 1;
1, 593775, 86493225, 86493225, 593775, 1;
		

Crossrefs

Programs

  • Mathematica
    t[n_, m_] := Binomial[n, 6*m]; Flatten@Table[Table[t[n, m], {m, 0, n/6}], {n, 0, 42, 6}]

Formula

Left-right symmetric: binomial(6*n,6*m) = binomial(6*n,6*(n-m)).
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