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 1-4 of 4 results.

A117267 Difference row triangle of A117189.

Original entry on oeis.org

1, 1, 2, 2, 3, 5, 4, 6, 9, 14, 7, 11, 17, 26, 40, 13, 20, 31, 48, 74, 114, 24, 37, 57, 88, 136, 210, 324, 44, 68, 105, 162, 250, 386, 596, 920, 81, 125, 193, 298, 460, 710, 1096, 1692, 2612, 149, 230, 355, 548, 846, 1306, 2016, 3112, 4804, 7416
Offset: 1

Views

Author

Gary W. Adamson, Mar 05 2006

Keywords

Comments

Take difference rows of A117189 (binomial transform of the tribonacci sequence, A000073); and reorient to a flush left format.

Examples

			Taking difference rows of A117189, we get:
   1,  2,  5, 14, 40, 114, ...
   1,  3,  9, 26, 74, ...
   2,  6, 17, 48, ...
   4, 11, 31, ...
   7, 20, ...
  13, ...
Reorient into the triangle:
  1;
  1,  2;
  2,  3,  5;
  4,  6,  9, 14;
  7, 11, 17, 26, 40;
  ...
		

Crossrefs

Cf. A000073 (1st column), A117268 (difference rows), A117189 (right diagonal).

Programs

  • PARI
    lista(nn) = my(va = Vec(-(x-1)^2/(-1+4*x-4*x^2+2*x^3) + O(x^(nn))), v = vector(nn)); v[1] = va; for (n=2, nn, v[n] = vector(nn-n+1, k, v[n-1][k+1] - v[n-1][k]);); my(list = List()); for (n=1, nn, my(i = n, j = 1); for (k=1, n, listput(list, v[i][j]); i--; j++;);); Vec(list); \\ Michel Marcus, Aug 10 2023

Extensions

More terms from Michel Marcus, Aug 10 2023

A115390 Binomial transform of tribonacci sequence A000073.

Original entry on oeis.org

0, 0, 1, 4, 12, 34, 96, 272, 772, 2192, 6224, 17672, 50176, 142464, 404496, 1148480, 3260864, 9258528, 26287616, 74638080, 211918912, 601698560, 1708394752, 4850622592, 13772308480, 39103533056, 111026143488, 315235058688, 895042726912, 2541282959872
Offset: 0

Views

Author

Jonathan Vos Post, Mar 08 2006

Keywords

Comments

See also A117189 Binomial transform of the tribonacci sequence A000073.

Examples

			1*0 = 0.
1*0 + 1*0 = 0.
1*0 + 2*0 + 1*1 = 1.
1*0 + 3*0 + 3*1 + 1* 1 = 4.
1*0 + 4*0 + 6*1 + 4*1 + 1*2 = 12.
		

Crossrefs

Cf. A000073, A117189. Trisection of A103685.

Programs

  • Haskell
    a115390 n = a115390_list !! n
    a115390_list = 0 : 0 : 1 : map (* 2) (zipWith (-) a115390_list
       (tail $ map (* 2) $ zipWith (-) a115390_list (tail a115390_list)))
    -- Reinhard Zumkeller, Oct 21 2011
  • Mathematica
    b[0]=b[1]=0;b[2]=1;b[n_]:=b[n]=b[n-1]+b[n-2]+b[n-3]; a[n_]:=Sum[n!/(k!*(n-k)!)*b[k],{k,0,n}];Table[a[n],{n,0,27}] (* Farideh Firoozbakht, Mar 11 2006 *)
  • Maxima
    sum(sum(binomial(j-1,k-1)*2^(j-k)*binomial(n-j+k-1,2*k-1),j,k,n-k),k,1,n); /* Vladimir Kruchinin, Aug 18 2010 */
    

Formula

a(n) = Sum_{k=0..n} C(n,k)*A000073(k).
O.g.f.: -x^2/(-1+4*x-4*x^2+2*x^3). - R. J. Mathar, Apr 02 2008
a(n) = sum(sum(binomial(j-1,k-1)*2^(j-k)*binomial(n-j+k-1,2*k-1),j,k,n-k),k,1,n). - Vladimir Kruchinin, Aug 18 2010

A117268 Triangle, binomial transform of the tribonacci sequence.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 4, 2, 3, 5, 7, 4, 6, 9, 14, 13, 7, 11, 17, 26, 40, 24, 13, 20, 31, 48, 74, 114, 44, 24, 37, 57, 88, 136, 210, 324, 81, 44, 68, 105, 162, 250, 386, 596, 920
Offset: 1

Views

Author

Gary W. Adamson, Mar 05 2006

Keywords

Comments

Leftmost column of the triangle = the tribonacci sequence A000073.
Rightmost diagonal of the triangle = A117189.

Examples

			Taking difference rows of A117267: (1; 1, 2; 2, 3, 5; 4, 6, 9, 14;...), we get A117268:
1;
1, 1;
2, 1, 2;
4, 2, 3, 5;
7, 4, 6, 9, 14;
13, 7, 11, 17, 26, 40;
24, 13, 20, 31, 48, 74, 114;
...
		

Crossrefs

Cf. A117267, A117189 (row sums), A000073.

Formula

Difference rows of A117267 become rows of A117268

A159035 a(0)=1=a(1), a(2)=2, a(3)=5; thereafter a(n+3)=4*a(n+2)-4*a(n+1)+2*a(n) for n>=1.

Original entry on oeis.org

1, 1, 2, 5, 14, 40, 114, 324, 920, 2612, 7416, 21056, 59784, 169744, 481952, 1368400, 3885280, 11031424, 31321376, 88930368, 252498816, 716916544, 2035531648, 5779458048, 16409538688, 46591385856, 132286304768, 375598753024
Offset: 0

Views

Author

Richard Choulet, Apr 03 2009

Keywords

Comments

A117189 prefixed by an initial 1; essentially a duplicate. - N. J. A. Sloane and R. J. Mathar, Apr 07 2009

Formula

G.f.: f(z)=((1-3*z+2*z^2-z^3)/(1-4*z+4*z^2-2*z^3))
Showing 1-4 of 4 results.