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 20 results.

A108286 Triangle read by rows; columns are simple recursive sequences.

Original entry on oeis.org

1, 3, 1, 6, 4, 1, 10, 11, 5, 1, 15, 26, 18, 6, 1, 21, 57, 58, 27, 7, 1, 28, 120, 179, 112, 38, 8, 1, 36, 247, 543, 453, 194, 51, 9, 1, 45, 502, 1636, 1818, 975, 310, 66, 10, 1
Offset: 1

Views

Author

Gary W. Adamson, May 31 2005

Keywords

Comments

Left column = triangular numbers; Col. 2, (1, 4, 11...) = A000295; Col. 3, (1, 5, 18...) = A000340; Col. 4, (1, 6, 27...) = A014825; Col.5, (1, 7, 38...) = A014827.

Examples

			First few rows of the triangle are:
1;
3, 1;
6, 4, 1;
10, 11; 5, 1;
15, 26, 18, 6, 1;
21, 57, 58, 27, 7, 1;
...
3rd offset column: (1, 5, 18, 58...) = "1", then a(r) = 3*a(r-1) + r; e.g. 58 = 3*18 + 4 since 58 is the fourth term in the third column.
		

Crossrefs

Formula

r-th term in n-th column: initial "1", then a(r) = n*a(r-1) + r. Diagonals of A108285 become the columns of A108286.

A145766 Partial sums of A020988.

Original entry on oeis.org

0, 2, 12, 54, 224, 906, 3636, 14558, 58248, 233010, 932060, 3728262, 14913072, 59652314, 238609284, 954437166, 3817748696, 15270994818, 61083979308, 244335917270, 977343669120, 3909374676522, 15637498706132, 62549994824574
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    lst={}; s=0; Do[s+=(s+=n+s); AppendTo[lst,s],{n,0,5!}]; lst
    Accumulate[LinearRecurrence[{5,-4},{0,2},30]] (* or *) LinearRecurrence[ {6,-9,4},{0,2,12},30] (* Harvey P. Dale, Sep 25 2013 *)

Formula

a(n) = Sum_{i=0..n} A020988(i). a(n+1)-a(n)=A020988(n+1).
a(n) = 2*(4^(n+1)-3n-4)/9 = 2*A014825(n). - R. J. Mathar, Oct 21 2008
G.f.: 2*x/((1-x)^2*(1-4*x)). [Colin Barker, Jan 11 2012]
a(n) = 6*a(n-1)-9*a(n-2)+4*a(n-3), for n>2, with {a(k)}={0,2,12}, k=0,1,2. - L. Edson Jeffery, Mar 01 2012

Extensions

Edited by R. J. Mathar, Oct 21 2008

A014851 Numbers k that divide s(k), where s(1)=1, s(j)=4*s(j-1)+j.

Original entry on oeis.org

1, 2, 3, 4, 6, 9, 10, 12, 18, 20, 21, 27, 30, 36, 42, 50, 54, 60, 63, 68, 78, 81, 84, 90, 100, 108, 110, 126, 147, 150, 156, 162, 171, 180, 189, 204, 210, 220, 234, 243, 250, 252, 270, 294, 300, 310, 324, 330, 340, 342, 378, 390, 410, 420, 441, 450, 468, 486
Offset: 1

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Author

Keywords

Crossrefs

s(n) = A014825(n).

Programs

  • Mathematica
    nxt[{k_,a_}]:={k+1,4a+k+1}; Transpose[Select[NestList[nxt,{1,1},500], Divisible[#[[2]],#[[1]]]&]][[1]] (* Harvey P. Dale, May 29 2013 *)

A089000 Square table, read by antidiagonals, of coefficients T(k,n) (row k; column n) defined by: T(k,n) = k*T(k,n-1)+ n; T(k,0) = 0.

Original entry on oeis.org

0, 1, 0, 2, 1, 0, 3, 3, 1, 0, 4, 6, 4, 1, 0, 5, 10, 11, 5, 1, 0, 6, 15, 26, 18, 6, 1, 0, 7, 21, 57, 58, 27, 7, 1, 0, 8, 28, 120, 179, 112, 38, 8, 1, 0, 9, 36, 247, 543, 453, 194, 51, 9, 1, 0, 10, 45, 502, 1636, 1818, 975, 310, 66, 10, 1, 0
Offset: 0

Views

Author

Philippe Deléham, Nov 02 2003

Keywords

Crossrefs

Rows begin:
{0, 1, 2, 3, 4, 5, 6, 7, 8, ...}:see A001477
{0, 1, 3, 6, 10, 15, 21, 28, ...} : see A000217
{0, 1, 4, 11, 26, 57, 120, 247, 502, ...} : see A000295
{0, 1, 5, 18, 58, 179, 543, 1636, ...} : see A000340
{0, 1, 6, 27, 112, 453, 1818, 7279, ...} : see A014825
{0, 1, 7, 38, 194, 975, 4881, 24412, ...} : see A014827
{0, 1, 8, 51, 310, 1865, 11196, 67183, ...}: see diagonals of triangle A088990
Diagonal begin:
{0, 1, 4, 18, 112, 975, 11196, ... } :see A062805
{0, 1, 5, 27, 194, 1865, ...} : see A023811
Column {3, 6, 11, 18, 27, 38, 51, ...} : see A010000

Programs

  • Mathematica
    Unprotect[Power]; 0^0=1; T[n_,k_]:=Sum[j*k^(n-j),{j,0,n}]; Table[T[n-k,k],{n,0,10},{k,0,n}]//Flatten (* Stefano Spezia, Apr 19 2025 *)

Formula

T(k, n)= (k^(n+1)- (k-1)*n - k)/(k-1)^2. T(k, n) = Sum(j, 0<=j<=n; j*k^(n-j)).

A108285 Triangle read by rows, generated from (1, 2, 3, ...).

Original entry on oeis.org

1, 1, 3, 1, 4, 6, 1, 5, 11, 10, 1, 6, 18, 26, 15, 1, 7, 27, 58, 57, 21, 1, 8, 38, 112, 179, 120, 28, 1, 9, 51, 194, 453, 543, 247, 36
Offset: 0

Views

Author

Gary W. Adamson, May 30 2005

Keywords

Comments

By diagonals (d=1,2,3,...) going to the left with (1,3,6,...) = d(1), these are sequences of the form (k-th term a(k) = d*a(k-1) + k). Example: 1, 7, 38, 194, ... (the 5th diagonal) = A014827, is generated by a(k) = 5*a(k-1) + k. Diagonal 2 = (1, 4, 11, 26, ...) = A000295; Diagonal 3 = (1, 5, 18, ...) = A000340; Diagonal 4 = (1, 6, 27, ...) = A014825.
Triangle A108243 is generated by analogous operations from (..., 3, 2, 1) instead of (1, 2, 3, ...).

Examples

			4th column (offset) = 10, 26, 58, 112, ...= f(x), x = 1, 2, 3; x^3 + 2x^2 + 3x + 4.
First few rows of the triangle are:
  1;
  1, 3;
  1, 4, 6;
  1, 5, 11, 10;
  1, 6, 18, 26, 15;
  1, 7, 27, 58, 57, 21;
  1, 8, 38, 112, 179, 120, 28;
  ...
		

Crossrefs

Formula

n-th column = f(x), x = 1, 2, 3, ...; x^(n) + 2*x^(n-1) + 3*x^(n-2) + ... + (n+1).

A145655 Partial sums of A080674.

Original entry on oeis.org

4, 24, 108, 448, 1812, 7272, 29116, 116496, 466020, 1864120, 7456524, 29826144, 119304628, 477218568, 1908874332, 7635497392, 30541989636, 122167958616, 488671834540, 1954687338240, 7818749353044, 31274997412264
Offset: 1

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Author

Keywords

Crossrefs

Cf. A080674.

Programs

  • Mathematica
    lst={};s=0;Do[s+=(s+=(s+=n));AppendTo[lst,s],{n,3*4!}];lst
    Accumulate[Table[4(4^n-1)/3,{n,0,40}]] (* or *) LinearRecurrence[{6,-9,4},{0,4,24},40] (* Harvey P. Dale, Nov 27 2013 *)

Formula

a(n) = sum_{i=0..n} A080674(i). a(n+1)-a(n) = A080674(n+1).
a(n) = 4*(4^(n+1)-3n-4)/9 = 4*A014825(n). - R. J. Mathar, Oct 21 2008
G.f.: 4x/((1-x)^2(1-4x)). - R. J. Mathar, Oct 21 2008
a(1)=4, a(2)=24, a(3)=108, a(n)=6*a(n-1)-9*a(n-2)+4*a(n-3). - Harvey P. Dale, Nov 27 2013

Extensions

Edited by R. J. Mathar, Oct 21 2008

A364378 Numbers whose representation in Jacobsthal greedy base (A265747) is palindromic.

Original entry on oeis.org

0, 1, 2, 4, 6, 9, 12, 20, 22, 27, 36, 41, 44, 60, 68, 84, 86, 97, 112, 123, 132, 143, 158, 169, 172, 204, 220, 252, 260, 292, 308, 340, 342, 363, 396, 417, 432, 453, 486, 507, 516, 537, 570, 591, 606, 627, 660, 681, 684, 748, 780, 844, 860, 924, 956, 1020, 1028
Offset: 1

Views

Author

Amiram Eldar, Jul 21 2023

Keywords

Comments

A128209(n) = A001045(n) + 1 is a term for n >= 3, since its representation is two 1's with n-3 0's between them.
A084639(n) is a term for n >= 1 since its representation is n 1's.
A014825(n) is a term for n >= 1 since its representation is n-1 0's interleaved with n 1's.

Examples

			The first 10 terms are:
   n  a(n)  A265747(a(n))
  --  ----  -------------
   1     0              0
   2     1              1
   3     2              2
   4     4             11
   5     6            101
   6     9            111
   7    12           1001
   8    20           1111
   9    22          10001
  10    27          10101
		

Crossrefs

Programs

  • Mathematica
    palJacobQ[n_] := PalindromeQ[A265747[n]]; Select[Range[0, 1000], palJacobQ] (* using A265747[n] *)
  • PARI
    is(n) = {my(dig = digits(A265747(n))); dig == Vecrev(dig);} \\ using A265747(n)

A368530 a(n) = Sum_{k=1..n} k^3 * 4^(n-k).

Original entry on oeis.org

0, 1, 12, 75, 364, 1581, 6540, 26503, 106524, 426825, 1708300, 6834531, 27339852, 109361605, 437449164, 1749800031, 6999204220, 27996821793, 111987293004, 447949178875, 1791796723500, 7167186903261, 28668747623692, 114674990506935, 458699962041564
Offset: 0

Views

Author

Seiichi Manyama, Dec 29 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=1, n, k^3*4^(n-k));

Formula

G.f.: x * (1+4*x+x^2)/((1-4*x) * (1-x)^4).
a(n) = 8*a(n-1) - 22*a(n-2) + 28*a(n-3) - 17*a(n-4) + 4*a(n-5).
a(n) = (11*4^(n+1) - (9*n^3 + 36*n^2 + 60*n + 44))/27.
a(0) = 0; a(n) = 4*a(n-1) + n^3.

A229463 Expansion of g.f. 1/((1-x)^2*(1-26*x)).

Original entry on oeis.org

1, 28, 731, 19010, 494265, 12850896, 334123303, 8687205886, 225867353045, 5872551179180, 152686330658691, 3969844597125978, 103215959525275441, 2683614947657161480, 69773988639086198495, 1814123704616241160886, 47167216320022270183053, 1226347624320579024759396
Offset: 0

Views

Author

Yahia Kahloune, Sep 24 2013

Keywords

Comments

This sequence was chosen to illustrate a method of solution.

Examples

			a(3) = (26^5 - 25*3 - 51)/625 = 19010.
		

Crossrefs

Programs

  • PARI
    my(x='x+O('x^18)); Vec(1/((1-26*x)*(1-x)^2)) \\ Elmo R. Oliveira, May 24 2025

Formula

a(n) = (26^(n+2) - 25*n - 51)/625.
In general, for the expansion of 1/((1-s*x)^2*(1-r*x)) with r>s>=1 we have the formula: a(n) = (r^(n+2)- s^(n+1)*((r-s)*n +(2*r-s)))/(r-s)^2.
From Elmo R. Oliveira, May 24 2025: (Start)
E.g.f.: exp(x)*(-51 - 25*x + 676*exp(25*x))/625.
a(n) = 28*a(n-1) - 53*a(n-2) + 26*a(n-3). (End)

A350717 a(n) = 4*a(n-1) - n - 1, for n > 0, a(0) = 1.

Original entry on oeis.org

1, 2, 5, 16, 59, 230, 913, 3644, 14567, 58258, 233021, 932072, 3728275, 14913086, 59652329, 238609300, 954437183, 3817748714, 15270994837, 61083979328, 244335917291, 977343669142, 3909374676545, 15637498706156, 62549994824599, 250199979298370, 1000799917193453, 4003199668773784
Offset: 0

Views

Author

Paul Curtz, Feb 03 2022

Keywords

Comments

Last digit (using 0 to 9) is of period 10: repeat [1, 2, 5, 6, 9, 0, 3, 4, 7, 8].

Crossrefs

Cf. A007583 (first differences), A014825, A160156.

Programs

  • Mathematica
    LinearRecurrence[{6, -9, 4}, {1, 2, 5}, 28] (* Amiram Eldar, Feb 03 2022 *)
  • PARI
    a(n) = if (n, 4*a(n-1) - n - 1, 1); \\ Michel Marcus, Feb 03 2022
    
  • Python
    print([(2**(2*n+1) + 3*n + 7)//9 for n in range(30)])
    # Gennady Eremin, Feb 05 2022

Formula

a(n) = (2^(2*n+1) + 3*n + 7)/9.
a(n) = 6*a(n-1) - 9*a(n-2) + 4*a(n-3), n >= 3.
a(n) = a(n-1) + A007583(n-1).
a(n) = 2*a(n-1) + A014825(n-1).
G.f.: (-2*x^2 + 4*x - 1)/((x - 1)^2*(4*x - 1)). - Thomas Scheuerle, Feb 03 2022
a(n) = -1 + 5*a(n-1) - 4*a(n-2), n >= 2.
a(n) = 1 + A160156(n-1), n >= 1.

Extensions

More terms from Michel Marcus, Feb 03 2022
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