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.

Showing 1-10 of 133 results. Next

A101615 Number of representations of n as a sum of the Jacobsthal numbers A078008 (2 is allowed twice as a part).

Original entry on oeis.org

1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 2
Offset: 0

Views

Author

Paul Barry, Dec 09 2004

Keywords

Comments

Partial sums are A101616.

Crossrefs

Cf. A026465.

Formula

G.f.: Product{k>=0, 1+x^A078008(k)}/2

A102564 A000120(A078008(n))-A078008(A000120(n)).

Original entry on oeis.org

0, 0, 1, -1, 2, 0, 1, 1, 4, 2, 3, 3, 4, 4, 5, 1, 8, 6, 7, 7, 8, 8, 9, 5, 10, 10, 11, 7, 12, 8, 9, 5, 16, 14, 15, 15, 16, 16, 17, 13, 18, 18, 19, 15, 20, 16, 17, 13, 22, 22, 23, 19, 24, 20, 21, 17, 26, 22, 23, 19, 24, 20, 21, 9, 32, 30, 31, 31, 32, 32, 33, 29, 34, 34, 35, 31, 36, 32, 33, 29, 38, 38, 39, 35, 40, 36, 37, 33, 42, 38, 39, 35, 40, 36
Offset: 0

Views

Author

Paul Barry, Jan 14 2005

Keywords

Comments

It would appear that a(2^(n+1))=2^n=A000079(n); a(2^(n+1)-1)+1=A078008(n); a(2^(n+1)+1)+1=2^n-1; a(4n+1)-a(2n+1)=n; a(8n+1)-a(4n+1)=2n.

Crossrefs

Cf. A102563, 102565.

A160760 Triangle read by rows, binomial transform of an infinite lower triangular Toeplitz matrix with A078008 in every column.

Original entry on oeis.org

1, 1, 1, 3, 2, 1, 9, 5, 3, 1, 27, 14, 8, 4, 1, 81, 41, 22, 12, 5, 1, 243, 122, 63, 34, 17, 6, 1, 729, 365, 185, 97, 51, 23, 7, 1, 2187, 1094, 550, 282, 148, 74, 30, 8, 1, 6561, 3281, 1644, 832, 430, 222, 104, 38, 9, 1
Offset: 0

Views

Author

Gary W. Adamson, May 25 2009

Keywords

Comments

Row sums = A025192: (1, 2, 6, 18, 54, 162, 486, 1458,...).
A triangle formed like Pascal's triangle, but with 3^n for n>=0 on the left border instead of 1. - Boris Putievskiy, Aug 19 2013

Examples

			First few rows of the triangle =
     1;
     1,    1;
     3,    2,    1;
     9,    5,    3,   1;
    27,   14,    8,   4,   1;
    81,   41,   22,  12,   5,   1;
   243,  122,   63,  34,  17,   6,   1;
   729,  365,  185,  97,  51,  23,   7,  1;
  2187, 1094,  550, 282, 148,  74,  30,  8, 1;
  6561, 3281, 1644, 832, 430, 222, 104, 38, 9, 1;
...
		

Crossrefs

Formula

A007318 * an infinite lower triangular Toeplitz matrix with A078008 in every column: (1, 0, 2, 2, 6, 10, 22, 42, 86,...).
Closed-form formula for arbitrary left and right borders of Pascal like triangle see A228196. - Boris Putievskiy, Aug 19 2013

Extensions

T(7,4) corrected by Georg Fischer, Oct 08 2021

A091598 Triangle read by rows: T(n,0) = A078008(n), T(n,m) = T(n-1,m-1) + T(n-1,m).

Original entry on oeis.org

1, 0, 1, 2, 1, 1, 2, 3, 2, 1, 6, 5, 5, 3, 1, 10, 11, 10, 8, 4, 1, 22, 21, 21, 18, 12, 5, 1, 42, 43, 42, 39, 30, 17, 6, 1, 86, 85, 85, 81, 69, 47, 23, 7, 1, 170, 171, 170, 166, 150, 116, 70, 30, 8, 1, 342, 341, 341, 336, 316, 266, 186, 100, 38, 9, 1, 682, 683, 682, 677, 652, 582, 452, 286, 138, 47, 10, 1
Offset: 0

Views

Author

Paul Barry, Jan 23 2004

Keywords

Comments

A Jacobsthal-Pascal triangle.

Examples

			Triangle starts as:
   1;
   0,  1;
   2,  1,  1;
   2,  3,  2,  1;
   6,  5,  5,  3,  1;
  10, 11, 10,  8,  4,  1;
  22, 21, 21, 18, 12,  5, 1;
  42, 43, 42, 39, 30, 17, 6, 1; ...
		

Crossrefs

Columns include A078008, A001045, A000975, A011377. Row sums give A084219.
Cf. A091597.

Programs

  • Mathematica
    T[n_, k_]:= If[k==0, (2^n + 2*(-1)^n)/3, If[k<0 || k>n, 0, T[n-1, k-1] + T[n-1, k]]]; Table[T[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Jun 04 2019 *)
  • PARI
    {T(n,k) = if(k==0, (2^n + 2*(-1)^n)/3, if(k<0 || k>n, 0, T(n-1,k-1) + T(n-1,k)))}; \\ G. C. Greubel, Jun 04 2019
    
  • Sage
    def T(n, k):
        if (k<0 or k>n): return 0
        elif (k==0): return (2^n + 2*(-1)^n)/3
        else: return T(n-1, k-1) + T(n-1, k)
    [[T(n, k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Jun 04 2019

Formula

k-th column has e.g.f. ((1-x)/(1-x-x^2))*(x/(1-x))^k.

A092900 A Jacobsthal sequence (A078008) to base 4.

Original entry on oeis.org

1, 0, 2, 2, 12, 22, 112, 222, 1112, 2222, 11112, 22222, 111112, 222222, 1111112, 2222222, 11111112, 22222222, 111111112, 222222222, 1111111112, 2222222222, 11111111112, 22222222222, 111111111112, 222222222222, 1111111111112
Offset: 0

Views

Author

Paul Barry, Mar 12 2004

Keywords

Examples

			a(8)= 1112 because A078008(8) = 86 (in base 10) = 64 + 16 + 4 + 2 = 1*(4^3) + 1*(4^2) + 1*(4^1) + 2.
		

Crossrefs

Cf. A081857.

Programs

  • PARI
    Vec((1-9*x^2+2*x^3)/((1-x)*(1+x)*(1-10*x^2)) + O(x^30)) \\ Colin Barker, Apr 01 2016

Formula

For n > 0, a(2*n+1) is represented as a string of n 2's and a(2*n) as a string of (n-1) 1's followed by a 2.
From Colin Barker, Apr 01 2016: (Start)
a(n) = (6+10*(-1)^n+10^(1/2*(-1+n))*(2-2*(-1)^n+sqrt(10)+(-1)^n*sqrt(10)))/18.
a(n) = (10^(n/2)+8)/9 for n even.
a(n) = (2^((n+1)/2)*5^((n-1)/2)-2)/9 for n odd.
a(n) = 11*a(n-2)-10*a(n-4) for n>3.
G.f.: (1-9*x^2+2*x^3) / ((1-x)*(1+x)*(1-10*x^2)).
(End)

A113678 Sequence array for A078008.

Original entry on oeis.org

1, 0, 1, 2, 0, 1, 2, 2, 0, 1, 6, 2, 2, 0, 1, 10, 6, 2, 2, 0, 1, 22, 10, 6, 2, 2, 0, 1, 42, 22, 10, 6, 2, 2, 0, 1, 86, 42, 22, 10, 6, 2, 2, 0, 1, 170, 86, 42, 22, 10, 6, 2, 2, 0, 1, 342, 170, 86, 42, 22, 10, 6, 2, 2, 0, 1, 682, 342, 170, 86, 42, 22, 10, 6, 2, 2, 0, 1, 1366, 682, 342, 170, 86
Offset: 0

Views

Author

Paul Barry, Nov 04 2005

Keywords

Comments

Row sums are A001045(n+1). Diagonal sums are A053088. Inverse is A113680.

Examples

			Triangle begins
1;
0, 1;
2, 0, 1;
2, 2, 0, 1;
6, 2, 2, 0, 1;
10, 6, 2, 2, 0, 1;
22, 10, 6, 2, 2, 0, 1;
		

Formula

Riordan array ((1-x)/(1-x-2x^2), x); Number triangle T(n, k)=if(k<=n, (2^(n-k)+2(-1)^(n-k))/3, 0); T(n, k)=sum{i=0..n, C(n-i, k)C(k, n-i)(2^i+2(-1)^i)/3}.

A128210 Number triangle T(n,k) = (-1)^(n-k)*[k<=n]*Product_{i=k+1..n} Sum_{j=0..i-1} A078008(j-1).

Original entry on oeis.org

1, -1, 1, 1, -1, 1, -3, 3, -3, 1, 15, -15, 15, -5, 1, -165, 165, -165, 55, -11, 1, 3465, -3465, 3465, -1155, 231, -21, 1, -148995, 148995, -148995, 49665, -9933, 903, -43, 1, 12664575, -12664575, 12664575
Offset: 0

Views

Author

Paul Barry, Feb 19 2007

Keywords

Comments

Inverse is A128208. Subdiagonals include -A001045(n+1) and A084175(n+1).

Examples

			Triangle begins:
        1;
       -1,      1;
        1,     -1,       1;
       -3,      3,      -3,     1;
       15,    -15,      15,    -5,     1;
     -165,    165,    -165,    55,   -11,   1;
     3465,  -3465,    3465, -1155,   231, -21,   1;
  -148995, 148995, -148995, 49665, -9933, 903, -43, 1;
  ...
		

A156550 a(n) = 5*(-1)^n*A078008(n).

Original entry on oeis.org

5, 0, 10, -10, 30, -50, 110, -210, 430, -850, 1710, -3410, 6830, -13650, 27310, -54610, 109230, -218450, 436910, -873810, 1747630, -3495250, 6990510, -13981010, 27962030, -55924050, 111848110, -223696210, 447392430, -894784850, 1789569710, -3579139410
Offset: 0

Views

Author

Paul Curtz, Feb 09 2009

Keywords

Crossrefs

Programs

Formula

a(n) = A140966(n)+A140966(n+2).
a(n) = 3*A140966(n)-A140966(n+1).
a(n+1) = 10*(-1)^n*A001045(n).
G.f.: 5*(1+x)/(1+x-2*x^2). - R. J. Mathar, Feb 23 2009
a(n) = (5*(2+(-2)^n))/3. - Colin Barker, Jun 10 2012
a(n) = -a(n-1) + 2*a(n-2) for n > 1. - Klaus Purath, Jan 30 2021
E.g.f.: 5*exp(-2*x)*(1 + 2*exp(3*x))/3. - Stefano Spezia, Jan 30 2021

Extensions

Edited and extended by R. J. Mathar Feb 23 2009

A160756 Triangle read by rows, infinite lower triangular Toeplitz matrix with A078008 in every column convolved with A001333.

Original entry on oeis.org

1, 0, 1, 2, 0, 1, 2, 2, 0, 3, 6, 2, 2, 0, 7, 10, 6, 2, 6, 0, 17, 22, 10, 6, 6, 14, 0, 41, 42, 22, 10, 18, 14, 34, 0, 99, 86, 42, 22, 30, 42, 34, 82, 0, 239, 170, 86, 42, 66, 70, 102, 82, 198, 0, 577
Offset: 0

Views

Author

Gary W. Adamson, May 25 2009

Keywords

Comments

Row sums = A001333: (1, 1, 3, 7, 17, 41,...). Sum of n-th row terms = rightmost term of next row.

Examples

			First few rows of the triangle =
1;
0, 1;
2, 0, 1;
2, 2, 0, 3;
6, 2, 2, 0, 7;
10, 6, 2, 6, 0, 17;
22, 10, 6, 6, 14, 0, 41;
42, 22, 10, 18, 14, 34, 0, 99;
86, 42, 22, 30, 42, 34, 82, 0, 239;
170, 86, 42, 66, 70, 102, 82, 198, 0, 577;
...
Example: row 4 = (6, 2, 2, 0, 7) = (6, 2, 2, 0, 1) * (1, 1, 1, 3, 7).
		

Crossrefs

Formula

Let M = an infinite lower triangular Toeplitz matrix with A078008 (1, 0, 2, 2, 6, 10, 22, 42, 86, 170,...). Let Q = the eigensequence of that triangle prefaced with a 1: (1, 1, 1, 3, 7, 17,...) where A001333 = (1, 1, 3, 7, 17,...). The triangle = M * Q.

A091085 a(n) = mod(A078008(n),10).

Original entry on oeis.org

1, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6, 0, 2, 2, 6
Offset: 0

Views

Author

Paul Barry, Dec 18 2003

Keywords

Comments

A078008(0), followed by A078008(1), A078008(2), A078008(3), A078008(4) repeating.

Crossrefs

Cf. A078008.

Programs

  • Mathematica
    LinearRecurrence[{0, 0, 0, 1}, {1, 0, 2, 2, 6}, 105] (* Georg Fischer, May 15 2019 *)

Formula

G.f.: (1+2x^2+2x^3+5x^4)/(1-x^4).
E.g.f.: 2cos(x)-sin(x)+3exp(-x)/2+5exp(x)/2-5.
a(n) = 2cos(Pi*n/2)-sin(Pi*n/2)+3(-1)^n/2+5/2-5*0^n.

Extensions

Terms a(75) ff. corrected by Georg Fischer, May 15 2019
Showing 1-10 of 133 results. Next