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 1-7 of 7 results.

A103285 Main diagonal of triangle A103284, in which row n+1 is formed by sorting, in ascending order, the result of the convolution of row n with {1,1}.

Original entry on oeis.org

1, 1, 2, 3, 5, 9, 16, 29, 53, 97, 179, 333, 623, 1172, 2215, 4201, 7992, 15241, 29122, 55745, 106879, 205223, 394637, 759973, 1465589, 2830273, 5473068, 10597365, 20544860, 39876331, 77481582, 150700968, 293380151, 571619362, 1114581628
Offset: 0

Views

Author

Paul D. Hanna, Jan 28 2005

Keywords

Crossrefs

Cf. A103284.

Programs

  • Haskell
    a103285 = last . a103284_row  -- Reinhard Zumkeller, Nov 19 2015
  • PARI
    {a(n)=local(A=vector(n+1,i,vector(i)),B);A[1][1]=1; for(k=1,n,B=vector(k+1);B[1]=1;B[k+1]=A[k][k]; for(i=2,k,B[i]=A[k][i]+A[k][i-1]); A[k+1]=vecsort(B));return(A[n+1][n+1])}
    

Formula

a(n) ~ 2^n*log_2(n)/(4n).

A257641 Central terms of triangle A103284.

Original entry on oeis.org

1, 1, 3, 9, 30, 102, 352, 1240, 4443, 16112, 58900, 216727, 801880, 2982327, 11147622, 41854916, 157805863, 597307573, 2268487476, 8639848112, 32999949539, 126498330700, 485441076004, 1865211479514, 7176111235446, 27644828367182, 106633724636570
Offset: 0

Views

Author

Reinhard Zumkeller, Nov 19 2015

Keywords

Comments

a(n) = A103284(2*n,n).

Crossrefs

Programs

  • Haskell
    a257641 n = a103284 (2 * n) n

A257646 Index of first row of triangle A103284 containing n.

Original entry on oeis.org

0, 2, 3, 4, 4, 5, 5, 9, 5, 11, 6, 13, 6, 7, 16, 6, 18, 7, 20, 7, 22, 23, 24, 7, 26, 27, 9, 29, 7, 8, 32, 33, 34, 8, 10, 37, 38, 8, 40, 41, 42, 43, 44, 8, 46, 47, 48, 49, 9, 51, 52, 53, 8, 12, 56, 57, 58, 59, 9, 61, 62, 63, 64, 9, 13, 67, 68, 69, 70, 71, 72
Offset: 1

Views

Author

Reinhard Zumkeller, Nov 19 2015

Keywords

Comments

a(n) <= n + 1.

Crossrefs

Programs

  • Haskell
    import Data.List (findIndex); import Data.Maybe (fromJust)
    a257646 n = fromJust $ findIndex (elem n) a103284_tabl

A107430 Triangle read by rows: row n is row n of Pascal's triangle (A007318) sorted into increasing order.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 4, 6, 1, 1, 5, 5, 10, 10, 1, 1, 6, 6, 15, 15, 20, 1, 1, 7, 7, 21, 21, 35, 35, 1, 1, 8, 8, 28, 28, 56, 56, 70, 1, 1, 9, 9, 36, 36, 84, 84, 126, 126, 1, 1, 10, 10, 45, 45, 120, 120, 210, 210, 252, 1, 1, 11, 11, 55, 55, 165, 165, 330, 330, 462, 462, 1
Offset: 0

Views

Author

Philippe Deléham, May 21 2005

Keywords

Comments

By rows, equals partial sums of A053121 reversed rows. Example: Row 4 of A053121 = (2, 0, 3, 0, 1) -> (1, 0, 3, 0, 2) -> (1, 1, 4, 4, 6). - Gary W. Adamson, Dec 28 2008, edited by Michel Marcus, Sep 22 2015

Examples

			Triangle begins:
1;
1,1;
1,1,2;
1,1,3,3;
1,1,4,4,6;
		

Crossrefs

A061554 is similar but with rows sorted into decreasing order.
Cf. A034868.
Cf. A053121. - Gary W. Adamson, Dec 28 2008
Cf. A103284.

Programs

  • Haskell
    import Data.List (sort)
    a107430 n k = a107430_tabl !! n !! k
    a107430_row n = a107430_tabl !! n
    a107430_tabl = map sort a007318_tabl
    -- Reinhard Zumkeller, May 26 2013
    
  • Magma
    /* As triangle */ [[Binomial(n,Floor(k/2)) : k in [0..n]]: n in [0.. 15]]; // Vincenzo Librandi, Sep 22 2015
    
  • Maple
    for n from 0 to 10 do sort([seq(binomial(n,k),k=0..n)]) od; # yields sequence in triangular form. - Emeric Deutsch, May 28 2005
  • Mathematica
    Flatten[ Table[ Sort[ Table[ Binomial[n, k], {k, 0, n}]], {n, 0, 12}]] (* Robert G. Wilson v, May 28 2005 *)
  • PARI
    for(n=0,20, for(k=0,n, print1(binomial(n,floor(k/2)), ", "))) \\ G. C. Greubel, May 22 2017

Formula

T(n,k) = C(n,floor(k/2)). - Paul Barry, Dec 15 2006; corrected by Philippe Deléham, Mar 15 2007
Sum_{k=0..n} T(n,k)*x^(n-k) = A127363(n), A127362(n), A127361(n), A126869(n), A001405(n), A000079(n), A127358(n), A127359(n), A127360(n) for x=-4,-3,-2,-1,0,1,2,3,4 respectively. - Philippe Deléham, Mar 29 2007

Extensions

More terms from Emeric Deutsch and Robert G. Wilson v, May 28 2005

A115323 Triangle, read by rows, where row n+1 is formed by sorting, in ascending order, the result of the convolution of row n (consisting of 2n+1 terms) with [1,1,1].

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 3, 1, 2, 3, 4, 5, 5, 7, 1, 3, 6, 7, 9, 12, 12, 14, 17, 1, 4, 10, 16, 17, 22, 28, 31, 33, 38, 43, 1, 5, 15, 30, 43, 43, 55, 67, 81, 81, 92, 102, 114, 1, 6, 21, 50, 88, 114, 116, 141, 165, 203, 216, 229, 254, 275, 308, 1, 7, 28, 77, 159, 252, 308, 318, 371, 422
Offset: 0

Views

Author

Paul D. Hanna, Jan 20 2006

Keywords

Examples

			Convolution of [1,1,1] with row 3 gives:
[1,1,1]*[1,2,3,4,5,5,7] = [1,3,6,9,12,14,17,12,7];
when sorted yields row 4: [1,3,6,7,9,12,12,14,17].
Triangle begins:
1;
1,1,1;
1,1,2,2,3;
1,2,3,4,5,5,7;
1,3,6,7,9,12,12,14,17;
1,4,10,16,17,22,28,31,33,38,43;
1,5,15,30,43,43,55,67,81,81,92,102,114;
1,6,21,50,88,114,116,141,165,203,216,229,254,275,308;
1,7,28,77,159,252,308,318,371,422,509,583,584,648,699,758,837; ...
		

Crossrefs

Cf. A103284 (variant), A115324 (central terms), A115325 (diagonal).

Programs

  • PARI
    T(n,k)=local(V);if(2*n=0,T(n-1,i-2))+if(i>0,T(n-1,i-1))+T(n-1,i)); V=vecsort(V);V[k+1]))

A103286 Triangle, read by rows, where row n+1 is formed by sorting, in ascending order, the result of the convolution of row n with {2,1}.

Original entry on oeis.org

1, 1, 2, 2, 2, 5, 4, 5, 6, 12, 8, 12, 14, 17, 30, 16, 30, 32, 40, 48, 77, 32, 76, 77, 94, 112, 136, 202, 64, 184, 202, 230, 265, 318, 384, 540, 128, 432, 540, 588, 662, 760, 901, 1086, 1464, 256, 992, 1464, 1512, 1716, 1912, 2182, 2562, 3073, 4014, 512, 2240
Offset: 0

Views

Author

Paul D. Hanna, Jan 28 2005

Keywords

Comments

Row sums are powers of 3. Main diagonal is A103287.

Examples

			Convolution of row 4 {4,5,6,12} with {2,1} = {8,14,17,30,12};
sort to obtain row 5: {8,12,14,17,30}.
Rows begin:
1,
1,2,
2,2,5,
4,5,6,12,
8,12,14,17,30,
16,30,32,40,48,77,
32,76,77,94,112,136,202,
64,184,202,230,265,318,384,540,
128,432,540,588,662,760,901,1086,1464,
256,992,1464,1512,1716,1912,2182,2562,3073,4014,...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=local(A=vector(n+1,i,vector(i)),B);A[1][1]=1; for(k=1,n,B=vector(k+1);B[1]=2*A[k][1];B[k+1]=A[k][k]; for(i=2,k,B[i]=2*A[k][i]+A[k][i-1]); A[k+1]=vecsort(B));return(A[n+1][k+1])}

A116908 Triangle, read by rows, where row n+1 is formed by sorting, in ascending order, the result of the convolution of row n with {1,2}.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 1, 3, 3, 5, 1, 4, 5, 6, 8, 1, 5, 8, 9, 11, 14, 1, 6, 13, 14, 17, 20, 24, 1, 7, 19, 24, 37, 31, 37, 44, 1, 8, 26, 43, 44, 51, 58, 68, 81, 1, 9, 34, 69, 81, 87, 95, 109, 126, 149, 1, 10, 43, 103, 149, 150, 168, 182, 204, 235, 274
Offset: 1

Views

Author

Jonathan Vos Post, Mar 16 2006

Keywords

Comments

See also: A103284 Triangle, read by rows, where row n+1 is formed by sorting, in ascending order, the result of the convolution of row n with {1,1}. Main diagonal is: 1, 2, 3, 5, 8, 14, 24, 44, 81, 149, 274,... This is lexicographically second of an infinite sequence of triangles such as Paul D. Hanna's A103284.

Examples

			Convolution of row 5 {1,4,5,6,8} with {1,2} = {1,5,9,11,14,8}; sort to obtain row 6: {1,5,8,9,11,14}.
Rows begin:
1,
1,2,
1,2,3,
1,3,3,5,
1,4,5,6,8,
1,5,8,9,11,14,
1,6,13,14,17,20,24,
1,7,19,24,37,31,37,44,
1,8,26,43,44,51,58,68,81,
1,9,34,69,81,87,95,109,126,149,
1,10,43,103,149,150,168,182,204,235,274,...
		

Crossrefs

Cf. A103284.
Showing 1-7 of 7 results.