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 11-12 of 12 results.

A284988 Number of distinct products i*j*k*l*m for 1 <= i <= j <= k <= l <= m <= n.

Original entry on oeis.org

1, 6, 21, 36, 91, 126, 266, 336, 441, 546, 994, 1120, 1890, 2184, 2562, 2856, 4482, 4932, 7392, 8052, 9042, 10032, 14377, 15092, 17237, 18887, 20812, 22297, 30635, 31856, 42783, 45240, 49023, 52806, 57707, 59436, 77623, 83083, 89180, 92365, 118188, 122248, 154188
Offset: 1

Views

Author

Seiichi Manyama, Apr 07 2017

Keywords

Links

Crossrefs

Cf. A027424, A027425, A100437.

A323334 Sum of distinct products i*j*k with 1 <= i, j, k <= n.

Original entry on oeis.org

1, 15, 90, 310, 990, 2220, 5300, 9660, 17130, 28670, 52848, 75696, 128541, 183393, 257628, 344316, 529038, 683316, 1001110, 1256010, 1607004, 2049490, 2837700, 3330636, 4177186, 5150340, 6273810, 7432702, 9779991, 11124711, 14381168, 16610640, 19542393, 23032799, 26873769
Offset: 1

Views

Author

Seiichi Manyama, Jan 11 2019

Keywords

Examples

			a(2) = 1 + 2 + 4 + 8 = 15.
a(3) = 1 + 2 + 3 + 4 + 6 + 8 + 9 + 12 + 18 + 27 = 90.

Links

Crossrefs

Column 3 of A321163.
Cf. A027425.

Programs

  • Mathematica
    a[n_] := Table[i j k, {i, n}, {j, n}, {k, n}] // Flatten // Union // Total;
Array[a, 35] (* Jean-François Alcover, Nov 25 2020 *)
  • Python
    def aupton(terms):
  alst, s, pset = [], 0, set()
  for n in range(1, terms):
    for i in range(1, n+1):
      for j in range(i, n+1):
        p = i*j*n # k = n
        if p not in pset:
          pset.add(p)
          s += p
    alst.append(s)
  return alst
print(aupton(36)) # Michael S. Branicky, Jan 15 2021
Previous Showing 11-12 of 12 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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