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.

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A205152 Least k such that n divides a difference between distinct averages of consecutive odd primes, as ordered in A204980.

Original entry on oeis.org

1, 1, 3, 4, 2, 5, 11, 4, 8, 23, 7, 12, 29, 11, 17, 42, 16, 32, 41, 23, 31, 22, 79, 30, 39, 29, 49, 38, 85, 37, 184, 84, 47, 113, 46, 57, 182, 56, 68, 212, 67, 111, 127, 80, 110, 79, 94, 109, 125, 93, 108, 92, 426, 107, 123, 106, 140, 122, 241, 121, 176, 454
Offset: 1

Views

Author

Clark Kimberling, Jan 26 2012

Keywords

Comments

For a guide to related sequences, see A204892.

Crossrefs

Programs

  • Mathematica
    (See the program at A205153.)

A205153 Least k such that n divides s(k)-s(j) for some j

Original entry on oeis.org

2, 2, 3, 4, 3, 4, 6, 4, 5, 8, 5, 6, 9, 6, 7, 10, 7, 9, 10, 8, 9, 8, 14, 9, 10, 9, 11, 10, 14, 10, 20, 14, 11, 16, 11, 12, 20, 12, 13, 22, 13, 16, 17, 14, 16, 14, 15, 16, 17, 15, 16, 15, 30, 16, 17, 16, 18, 17, 23, 17, 20, 31, 18, 20, 18, 19, 20, 19, 21, 20, 22, 20, 24
Offset: 1

Views

Author

Clark Kimberling, Jan 26 2012

Keywords

Comments

See A204892 for a discussion and guide to related sequences.

Crossrefs

Programs

  • Mathematica
    s[n_] := s[n] = (Prime[n + 1] + Prime[n + 2])/2; z1 = 1100; z2 = 80;
    Table[s[n], {n, 1, 30}]     (* A024675 *)
    u[m_] := u[m] = Flatten[Table[s[k] - s[j], {k, 2, z1}, {j, 1, k - 1}]][[m]]
    Table[u[m], {m, 1, z1}]     (* A204980 *)
    v[n_, h_] := v[n, h] = If[IntegerQ[u[h]/n], h, 0]
    w[n_] := w[n] = Table[v[n, h], {h, 1, z1}]
    d[n_] := d[n] = First[Delete[w[n], Position[w[n], 0]]]
    Table[d[n], {n, 1, z2}]     (* A205152 *)
    k[n_] := k[n] = Floor[(3 + Sqrt[8 d[n] - 1])/2]
    m[n_] := m[n] = Floor[(-1 + Sqrt[8 n - 7])/2]
    j[n_] := j[n] = d[n] - m[d[n]] (m[d[n]] + 1)/2
    Table[k[n], {n, 1, z2}]       (* A205153 *)
    Table[j[n], {n, 1, z2}]       (* A205154 *)
    Table[s[k[n]], {n, 1, z2}]    (* A205372 *)
    Table[s[j[n]], {n, 1, z2}]    (* A205373 *)
    Table[s[k[n]] - s[j[n]], {n, 1, z2}]      (* A205374 *)
    Table[(s[k[n]] - s[j[n]])/n, {n, 1, z2}]  (* A205375 *)
Showing 1-2 of 2 results.