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.

A344726 Square array T(n,k), n >= 1, k >= 1, read by antidiagonals downwards, where T(n,k) = Sum_{j=1..n} (-1)^(j+1) * floor(n/j)^k.

Original entry on oeis.org

1, 1, 1, 1, 3, 3, 1, 7, 9, 2, 1, 15, 27, 12, 4, 1, 31, 81, 56, 22, 4, 1, 63, 243, 240, 118, 30, 6, 1, 127, 729, 992, 610, 196, 44, 4, 1, 255, 2187, 4032, 3094, 1230, 324, 48, 7, 1, 511, 6561, 16256, 15562, 7564, 2336, 448, 71, 7, 1, 1023, 19683, 65280, 77998, 45990, 16596, 3840, 685, 83, 9
Offset: 1

Views

Author

Seiichi Manyama, May 27 2021

Keywords

Examples

			Square array begins:
  1,  1,   1,    1,    1,     1, ...
  1,  3,   7,   15,   31,    63, ...
  3,  9,  27,   81,  243,   729, ...
  2, 12,  56,  240,  992,  4032, ...
  4, 22, 118,  610, 3094, 15562, ...
  4, 30, 196, 1230, 7564, 45990, ...
		

Crossrefs

Columns k=1..5 give A059851, A344720, A344721, A344722, A344723.
T(n,n) gives A344724.
Cf. A344725.

Programs

  • Mathematica
    T[n_, k_] := Sum[(-1)^(j + 1) * Quotient[n, j]^k, {j, 1, n}]; Table[T[k, n - k + 1], {n, 1, 11}, {k, 1, n}] // Flatten (* Amiram Eldar, May 27 2021 *)
  • PARI
    T(n, k) = sum(j=1, n, (-1)^(j+1)*(n\j)^k);
    
  • PARI
    T(n, k) = sum(j=1, n, sumdiv(j, d, (-1)^(j/d+1)*(d^k-(d-1)^k)));

Formula

G.f. of column k: (1/(1 - x)) * Sum_{j>=1} (j^k - (j - 1)^k) * x^j/(1 + x^j).
T(n,k) = Sum_{j=1..n} Sum_{d|j} (-1)^(j/d + 1) * (d^k - (d - 1)^k).

A350106 Square array T(n,k), n >= 1, k >= 1, read by antidiagonals downwards, where T(n,k) = Sum_{j=1..n} j * floor(n/j)^k.

Original entry on oeis.org

1, 1, 4, 1, 6, 8, 1, 10, 14, 15, 1, 18, 32, 31, 21, 1, 34, 86, 87, 45, 33, 1, 66, 248, 295, 153, 81, 41, 1, 130, 734, 1095, 669, 309, 101, 56, 1, 258, 2192, 4231, 3201, 1521, 443, 150, 69, 1, 514, 6566, 16647, 15765, 8373, 2633, 722, 191, 87, 1, 1026, 19688, 66055, 78393, 48321, 17411, 4746, 1005, 253, 99
Offset: 1

Views

Author

Seiichi Manyama, Dec 14 2021

Keywords

Examples

			Square array begins:
   1,   1,   1,    1,     1,      1,      1, ...
   4,   6,  10,   18,    34,     66,    130, ...
   8,  14,  32,   86,   248,    734,   2192, ...
  15,  31,  87,  295,  1095,   4231,  16647, ...
  21,  45, 153,  669,  3201,  15765,  78393, ...
  33,  81, 309, 1521,  8373,  48321, 284709, ...
  41, 101, 443, 2633, 17411, 119321, 828323, ...
		

Crossrefs

Columns k=1..3 give A024916, A350107, A350108.
T(n,n) gives A350109.

Programs

  • Mathematica
    T[n_, k_] := Sum[j * Floor[n/j]^k, {j, 1, n}]; Table[T[k, n - k + 1], {n, 1, 11}, {k, 1, n}] // Flatten (* Amiram Eldar, Dec 14 2021 *)
  • PARI
    T(n, k) = sum(j=1, n, j*(n\j)^k);
    
  • PARI
    T(n, k) = sum(j=1, n, j*sumdiv(j, d, (d^k-(d-1)^k)/d));

Formula

G.f. of column k: (1/(1 - x)) * Sum_{j>=1} (j^k - (j - 1)^k) * x^j/(1 - x^j)^2.
T(n,k) = Sum_{j=1..n} j * Sum_{d|j} (d^k - (d - 1)^k)/d.

A350122 Square array T(n,k), n >= 1, k >= 1, read by antidiagonals downwards, where T(n,k) = Sum_{j=1..n} floor(n/(2*j-1))^k.

Original entry on oeis.org

1, 1, 2, 1, 4, 4, 1, 8, 10, 5, 1, 16, 28, 17, 7, 1, 32, 82, 65, 27, 9, 1, 64, 244, 257, 127, 41, 11, 1, 128, 730, 1025, 627, 225, 55, 12, 1, 256, 2188, 4097, 3127, 1313, 353, 70, 15, 1, 512, 6562, 16385, 15627, 7809, 2419, 522, 93, 17, 1, 1024, 19684, 65537, 78127, 46721, 16841, 4114, 759, 115, 19
Offset: 1

Views

Author

Seiichi Manyama, Dec 16 2021

Keywords

Examples

			Square array begins:
   1,  1,   1,    1,     1,      1,      1, ...
   2,  4,   8,   16,    32,     64,    128, ...
   4, 10,  28,   82,   244,    730,   2188, ...
   5, 17,  65,  257,  1025,   4097,  16385, ...
   7, 27, 127,  627,  3127,  15627,  78127, ...
   9, 41, 225, 1313,  7809,  46721, 280065, ...
  11, 55, 353, 2419, 16841, 117715, 823673, ...
		

Crossrefs

Columns k=1..3 give A060831, A350143, A350144.
T(n,n) gives A350145.
Cf. A344725.

Programs

  • Mathematica
    T[n_, k_] := Sum[Floor[n/(2*j - 1)]^k, {j, 1, n}]; Table[T[k, n - k + 1], {n, 1, 11}, {k, 1, n}] // Flatten (* Amiram Eldar, Dec 17 2021 *)
  • PARI
    T(n, k) = sum(j=1, n, (n\(2*j-1))^k);
    
  • PARI
    T(n, k) = sum(j=1, n, sumdiv(j, d, j/d%2*(d^k-(d-1)^k)));

Formula

G.f. of column k: (1/(1 - x)) * Sum_{j>=1} (j^k - (j - 1)^k) * x^j/(1 - x^(2*j)).
T(n,k) = Sum_{j=1..n} Sum_{d|j, j/d odd} d^k - (d - 1)^k.

A356250 Square array T(n,k), n >= 1, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=1..n} (j * floor(n/j))^k.

Original entry on oeis.org

1, 1, 2, 1, 4, 3, 1, 8, 8, 4, 1, 16, 22, 15, 5, 1, 32, 62, 57, 21, 6, 1, 64, 178, 219, 91, 33, 7, 1, 128, 518, 849, 405, 185, 41, 8, 1, 256, 1522, 3315, 1843, 1053, 247, 56, 9, 1, 512, 4502, 13017, 8541, 6065, 1523, 402, 69, 10, 1, 1024, 13378, 51339, 40171, 35253, 9571, 2948, 545, 87, 11
Offset: 1

Views

Author

Seiichi Manyama, Jul 31 2022

Keywords

Examples

			Square array begins:
  1,  1,   1,    1,    1,     1,      1, ...
  2,  4,   8,   16,   32,    64,    128, ...
  3,  8,  22,   62,  178,   518,   1522, ...
  4, 15,  57,  219,  849,  3315,  13017, ...
  5, 21,  91,  405, 1843,  8541,  40171, ...
  6, 33, 185, 1053, 6065, 35253, 206345, ...
  7, 41, 247, 1523, 9571, 61091, 394987, ...
		

Crossrefs

Columns k=0..3 give A001477, A024916, A350123, A356249.
T(n,n) gives A356238.
Cf. A344725.

Programs

  • Mathematica
    T[n_, k_] := Sum[(j * Floor[n/j])^k, {j, 1, n}]; Table[T[k, n - k], {n, 1, 11}, {k, 1, n}] // Flatten (* Amiram Eldar, Jul 31 2022 *)
  • PARI
    T(n, k) = sum(j=1, n, (j*(n\j))^k);
    
  • PARI
    T(n, k) = if(k==0, n, sum(j=1, n, j^k*sumdiv(j, d, 1-(1-1/d)^k)));

Formula

T(n,k) = Sum_{j=1..n} j^k * Sum_{d|j} (1 - (1 - 1/d)^k) for k > 0.
Showing 1-4 of 4 results.