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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A094456 Triangle T(n,k), 0<=k<=n, read by rows; given by [0, 1, 0, 2, 0, 3, 0, 4, 0, 5, 0, ...] DELTA [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...] where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 1, 0, 1, 2, 0, 1, 5, 5, 0, 1, 10, 22, 14, 0, 1, 19, 70, 93, 42, 0, 1, 36, 201, 421, 386, 132, 0, 1, 69, 559, 1657, 2324, 1586, 429, 0, 1, 134, 1548, 6162, 11836, 12136, 6476, 1430, 0, 1, 263, 4316, 22445, 55843, 76928, 60948, 26333, 4862, 0, 1, 520, 12163, 81451, 254415, 444666, 467426, 297335, 106762, 16796
Offset: 0

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Author

Philippe Deléham, Jun 04 2004

Keywords

Comments

Triangle :
1;
0, 1;
0, 1, 2;
0, 1, 5, 5;
0, 1, 10, 22, 14;
...
The alternating sum is (-1)^n = A033999(n). - F. Chapoton, Mar 18 2023

Crossrefs

Cf. A000108 (main diagonal), A033999, A084938, A090365 (row sums).

Formula

Sum_{k=0..n} T(n,k) = A090365(n).

A160692 Iteration of (k terms=k, followed by 2^k-k terms=0), beginning with k=0.

Original entry on oeis.org

0, 1, 0, 2, 2, 0, 0, 3, 3, 3, 0, 0, 0, 0, 0, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 5, 5, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 6, 6, 6, 6, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Reinhard Zumkeller, May 24 2009

Keywords

Comments

For n with 2^k - 1 <= n < 2^k + k-1: a(n) = k;
for n with 2^k + k-1 <= n < 2^(k+1) - 1: a(n) = 0.

Crossrefs

Formula

a(n) = f(n,0) with f(n,k) = if n<2^k then (if n

A210792 Triangle of coefficients of polynomials v(n,x) jointly generated with A210791; see the Formula section.

Original entry on oeis.org

1, 1, 2, 1, 5, 3, 1, 10, 11, 5, 1, 19, 28, 25, 8, 1, 36, 62, 81, 50, 13, 1, 69, 129, 218, 193, 98, 21, 1, 134, 261, 533, 597, 442, 185, 34, 1, 263, 522, 1235, 1631, 1559, 952, 343, 55, 1, 520, 1040, 2773, 4129, 4763, 3758, 1985, 625, 89, 1, 1033, 2071
Offset: 1

Author

Clark Kimberling, Mar 26 2012

Keywords

Comments

Row n starts with 1 and ends with F(n+1), where F=A000045 (Fibonacci numbers).
Column 2: A052944.
Row sums: A000244 (powers of 3).
Alternating row sums: A001333.
For a discussion and guide to related arrays, see A208510.
Subtriangle of the triangle given by (1, 0, 1/2, 3/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (0, 2, -1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - Philippe Deléham, Mar 29 2012

Examples

			First five rows:
  1;
  1,  2;
  1,  5,  3;
  1, 10, 11,  5;
  1, 19, 28, 25,  8;
First three polynomials v(n,x):
  1
  1 + 2x
  1 + 5x + 3x^2
From _Philippe Deléham_, Mar 29 2012: (Start)
(1, 0, 1/2, 3/2, 0, 0, 0, ...) DELTA (0, 2, -1/2, -1/2, 0, 0, 0, ...) begins:
  1;
  1,   0;
  1,   2,   0;
  1,   5,   3,   0;
  1,  10,  11,   5,   0;
  1,  19,  28,  25,   8,   0;
  1,  36,  62,  81,  50,  13,   0;
  1,  69, 129, 218, 193,  98,  21,   0; (End)
		

Crossrefs

Programs

  • Mathematica
    u[1, x_] := 1; v[1, x_] := 1; z = 16;
    u[n_, x_] := u[n - 1, x] + (x + j)*v[n - 1, x] + c;
    d[x_] := h + x; e[x_] := p + x;
    v[n_, x_] := d[x]*u[n - 1, x] + e[x]*v[n - 1, x] + f;
    j = 0; c = 0; h = -1; p = 2; f = 0;
    Table[Expand[u[n, x]], {n, 1, z/2}]
    Table[Expand[v[n, x]], {n, 1, z/2}]
    cu = Table[CoefficientList[u[n, x], x], {n, 1, z}];
    TableForm[cu]
    Flatten[%]    (* A210791 *)
    cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
    TableForm[cv]
    Flatten[%]    (* A210792 *)
    Table[u[n, x] /. x -> 1, {n, 1, z}]   (* A007051 *)
    Table[v[n, x] /. x -> 1, {n, 1, z}]   (* A000244 *)
    Table[u[n, x] /. x -> -1, {n, 1, z}]  (* A001129 *)
    Table[v[n, x] /. x -> -1, {n, 1, z}]  (* A001333 *)

Formula

u(n,x) = u(n-1,x) + x*v(n-1,x),
v(n,x) = (x-1)*u(n-1,x) + (x+2)*v(n-1,x),
where u(1,x)=1, v(1,x)=1.
From Philippe Deléham, Mar 29 2012: (Start)
As DELTA-triangle T(n,k) with 0 <= k <= n:
G.f.: (1 - 2*x - y*x + 3*y*x^2 - y^2*x^2)/(1 - 3*x - y*x + 2*x^2 + 2*y*x^2 - y^2*x^2).
T(n,k) = 3*T(n-1,k) + T(n-1,k-1) - 2*T(n-2,k) - 2*T(n-2,k-1) + T(n-2,k-2), T(0,0) = T(1,0) = T(2,0) = 1, T(2,1) = 2, T(1,1) = T(2,2) = 0 and T(n,k) = 0 if k < 0 or if k > n. (End)

A132736 Row sums of triangle A132735.

Original entry on oeis.org

1, 2, 5, 10, 19, 36, 69, 134, 263, 520, 1033, 2058, 4107, 8204, 16397, 32782, 65551, 131088, 262161, 524306, 1048595, 2097172, 4194325, 8388630, 16777239, 33554456, 67108889, 134217754, 268435483, 536870940, 1073741853, 2147483678
Offset: 0

Author

Gary W. Adamson, Aug 26 2007

Keywords

Comments

Apart from first term, the same as A052944. - R. J. Mathar, Jun 12 2008

Examples

			a(4) = 19 = sum of row 4 terms of triangle A132735: (1 + 5 + 7 + 5 + 1).
a(3) = 10 = (1, 3, 3, 1) dot (1, 1, 2, 0) = (1 + 3 + 6 + 0).
		

Crossrefs

Cf. A132735.

Programs

  • Magma
    [1] cat [2^n + n-1: n in [1..30]]; // G. C. Greubel, Feb 14 2021
  • Maple
    a:= proc(n) option remember; if n=0 then 1 else add((binomial(n,j)+1), j=0..n-1) fi end: seq(a(n), n=0..31);# Zerinvary Lajos, Mar 29 2009
  • Mathematica
    Table[2^n + n-1 + Boole[n==0], {n,0,30}] (* G. C. Greubel, Feb 14 2021 *)
  • Sage
    [1]+[2^n + n-1 for n in (1..30)] # G. C. Greubel, Feb 14 2021
    

Formula

Binomial transform of [1, 1, 2, 0, 2, 0, 2, 0, 2, ...].
From Colin Barker, Aug 12 2012: (Start)
a(n) = 4*a(n-1) -5*a(n-2) +2*a(n-3) for n>3.
G.f.: (1 -2*x +2*x^2 -2*x^3)/((1-x)^2*(1-2*x)). (End)
From G. C. Greubel, Feb 14 2021: (Start)
a(n) = 2^n + n - 1 + [n=0].
E.g.f.: 1 - (1-x)*exp(x) + exp(2*x). (End)

Extensions

More terms from R. J. Mathar, Jun 12 2008

A247241 In base 2, smallest positive integer k such that k contains all possible strings of n binary digits.

Original entry on oeis.org

2, 19, 558, 272060, 34949682936, 297564712194085870576, 10932581082490851526951746612437309648864, 7425338450010038712278392695279246718801455644988538421150211866664645481447360
Offset: 1

Author

Anthony Sand, Nov 28 2014

Keywords

Comments

In base 2, there are 2^n distinct strings of n digits and the smallest positive integer to contain all of them will have 2^n+(n-1) digits (see A052944). For example, there are 2^2 = 4 distinct strings of two digits: 00, 01, 10, 11. All of them are represented in the 5-digit binary number 10011 = 19 in base 10.

Examples

			n = 1: a(1) = 2 = 10 in base 2, which contains 2 distinct strings of one digit: 1, 0.
n = 2: a(2) = 19 = 10011, which contains 4 distinct strings of two digits: 10, 00, 01, 11.
n = 3: a(3) = 558 = 1000101110, which contains 8 distinct strings of three digits: 100, 000, 001, 010, 101, 011, 111, 110.
n = 4: a(4) = 272060 = 1000010011010111100, which contains 16 distinct strings of four digits: 1000, 0000, 0001, 0010, 0100, 1001, 0011, 0110, 1101, 1010, 0101, 1011, 0111, 1111, 1110, 1100.
		

Crossrefs

A342298 a(n) is the greatest k such that A342263(k) = n.

Original entry on oeis.org

2, 25, 931, 504455, 67539587599, 585462196329239562271, 21690980800898420269408456526391711768639, 14792097944732868603877386771665610972834204784426907551800717772696470224928895
Offset: 0

Author

Rémy Sigrist, Mar 07 2021

Keywords

Crossrefs

Programs

  • PARI
    See Links section.

Formula

A070939(a(n)) = A052944(n+1).

A309832 Maximum length of a binary sequence S such that every pair of subwords of length n in S is of Hamming distance at least 2.

Original entry on oeis.org

3, 5, 7, 14, 23, 41, 74
Offset: 2

Author

Yeow Meng Chee, Aug 19 2019

Keywords

Crossrefs

A309833 Maximum length of a binary sequence S such that any pair of distinct subwords of length n in S is of Hamming distance at least 3.

Original entry on oeis.org

4, 5, 7, 12, 20, 25, 39, 71
Offset: 3

Author

Yeow Meng Chee, Aug 19 2019

Keywords

Crossrefs

A373895 a(n) = ceiling((2^n+n-1)/n).

Original entry on oeis.org

2, 3, 4, 5, 8, 12, 20, 33, 58, 104, 188, 343, 632, 1172, 2186, 4097, 7712, 14565, 27596, 52430, 99866, 190652, 364724, 699052, 1342179, 2581112, 4971028, 9586982, 18512792, 35791396, 69273668, 134217729, 260301050, 505290272, 981706812, 1908874355, 3714566312, 7233629132, 14096302922, 27487790696
Offset: 1

Author

Eric W. Weisstein, Jun 21 2024

Keywords

Comments

a(n) is the irregularity strength of the hypercube graph Q_n for n >= 2.

Crossrefs

Programs

  • Mathematica
    Array[Ceiling[(2^# + # - 1)/#] &, 120] (* Michael De Vlieger, Jun 21 2024 *)

A091264 Matrix defined by a(n,k) = 2^n + (k-1), read by antidiagonals.

Original entry on oeis.org

0, 1, 1, 3, 2, 2, 7, 4, 3, 3, 15, 8, 5, 4, 4, 31, 16, 9, 6, 5, 5, 63, 32, 17, 10, 7, 6, 6, 127, 64, 33, 18, 11, 8, 7, 7, 255, 128, 65, 34, 19, 12, 9, 8, 8, 511, 256, 129, 66, 35, 20, 13, 10, 9, 9, 1023, 512, 257, 130, 67, 36, 21, 14, 11, 10, 10, 2047, 1024, 513, 258, 131, 68, 37, 22
Offset: 0

Author

Ross La Haye, Feb 23 2004

Keywords

Examples

			{0};
{1,1};
{3,2,2};
{7,4,3,3};
{15,8,5,4,4};
{31,16,9,6,5,5};
{63,32,17,10,7,6,6};
a(5,3) = 34 because 2^5 + (3-1) = 34.
		

Crossrefs

Rows: a(0, k) = A001477(k), a(1, k) = A000027(k+1) etc. etc. Columns: a(n, 0) = A000225(n). a(n, 1) = A000079(n). a(n, 2) = A000051(n). a(n, 3) = A052548(n). a(n, 4) = A062709(n). Diagonals: a(n, n+3) = A052968(n+1). a(n, n+2) = A005126(n). a(n, n+1) = A006127(n). a(n, n) = A052944(n). a(n, n-1) = A083706(n-1). Also note that the sums of the antidiagonals = the partial sums of the main diagonal, i.e., a(n, n).

Programs

  • Mathematica
    Flatten[ Table[ Table[ a[i, n - i], {i, n, 0, -1}], {n, 0, 11}]] (* both from Robert G. Wilson v, Feb 26 2004 *)
    Table[a[n, k], {n, 0, 10}, {k, 0, 10}] // TableForm (* to view the table *)

Formula

For k > 0, a(n, k)= a(n, k-1) + 1.
a(n, k) = 2^n + (k-1).

Extensions

More terms from Robert G. Wilson v, Feb 23 2004
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