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.

A360377 a(n) = number of the row of the Wythoff array (A035513) that includes prime(n).

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 7, 8, 6, 2, 8, 6, 10, 17, 2, 21, 23, 24, 26, 11, 7, 12, 20, 1, 6, 39, 40, 10, 26, 17, 49, 8, 53, 21, 14, 36, 6, 63, 40, 10, 69, 27, 7, 46, 76, 2, 81, 33, 54, 88, 1, 92, 14, 23, 38, 64, 66, 42, 27, 74, 18, 80, 84, 53, 54, 90, 94, 59, 60, 24
Offset: 1

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Author

Clark Kimberling, Feb 04 2023

Keywords

Comments

Conjecture: every primitive row number, as defined in A332938, occurs infinitely many times in this sequence.

Examples

			The 10th prime is 29, which occurs in row 7, so a(10) = 2.
		

Crossrefs

Programs

  • Mathematica
    W[n_, k_] := Fibonacci[k + 1] Floor[n*GoldenRatio] + (n - 1) Fibonacci[k];
    t = Table[W[n, k], {n, 100}, {k, 1, 20}];
    a[n_] := Select[Range[100], MemberQ[t[[#]], Prime[n]] &]
    Flatten[Table[a[n], {n, 1, 100}]]

Formula

Every prime p has a unique representation p = p(m,k) = F(k+1)*[m*tau] + (m-1)*F(k), where F(h) = A000045(h) = h-th Fibonacci number, [ ] = floor, and tau = (1+sqrt(5))/2 = golden ratio, as in A001622. Here, a(n) is the number m such that prime(n) = p(m,k) for some k.

A360378 a(n) = number of the column of the Wythoff array (A035513) that includes prime(n).

Original entry on oeis.org

2, 3, 4, 2, 3, 6, 1, 1, 2, 5, 2, 3, 2, 1, 6, 1, 1, 1, 1, 3, 4, 3, 2, 10, 5, 1, 1, 4, 2, 3, 1, 5, 1, 3, 4, 2, 6, 1, 2, 5, 1, 3, 6, 2, 1, 9, 1, 3, 2, 1, 12, 1, 5, 4, 3, 1, 2, 1, 2, 1, 3, 4, 1, 2, 1, 5, 1, 2, 1, 1, 2, 3, 3, 1, 2, 1, 1, 2, 3, 3, 5, 2, 2, 1, 2, 3
Offset: 1

Views

Author

Clark Kimberling, Feb 04 2023

Keywords

Comments

Conjecture: every positive integer occurs infinitely many times in this sequence.

Examples

			The 10th prime is 29, which occurs in column 5, so a(10) = 5.
		

Crossrefs

Programs

  • Mathematica
    W[n_, k_] := Fibonacci[k + 1] Floor[n*GoldenRatio] + (n - 1) Fibonacci[k];
    t = Table[W[n, k], {k, 200}, {n, 1, 600}];
    a[n_] := Select[Range[200], MemberQ[t[[#]], Prime[n]] &]
    Flatten[Table[a[n], {n, 1, 100}]]

Formula

Every prime p has a unique representation p = p(m,k) = F(k+1)*[m*tau] + (m-1)*F(k), where F(h) = A000045(h) = h-th Fibonacci number, [ ] = floor, and tau = (1+sqrt(5))/2 = golden ratio, as in A001622. Here, a(n) is the number k such that prime(n) = p(m,k) for some m.

A360380 a(n) = number of the diagonal of the Wythoff array, A035513, that includes prime(n). See Comments.

Original entry on oeis.org

1, 2, 3, 0, 1, 5, -6, -7, -4, 3, -6, -3, -8, -16, 4, -20, -22, -23, -25, -8, -3, -9, -18, 9, -1, -38, -39, -6, -24, -14, -48, -3, -52, -18, -10, -34, 0, -62, -38, -5, -68, -24, -1, -44, -75, 7, -80, -30, -52, -87, 11, -91, -9, -19, -35, -100, -62, -103, -64
Offset: 1

Views

Author

Clark Kimberling, Feb 07 2023

Keywords

Comments

The indexing of diagonals is given in A191360. Conjecture: every integer occurs infinitely many times in this sequence; i.e., every diagonal includes infinitely many primes.

Examples

			a(n) = A191360(prime(n)).
		

Crossrefs

Programs

  • Mathematica
    w[n_, k_] := Fibonacci[k + 1] Floor[n*GoldenRatio] + (n - 1) Fibonacci[k];
    t = Table[w[n - k + 1, k], {n, 300}, {k, n, 1, -1}];
    Map[1 + #[[1]] - 2 #[[2]] &, Most[Reap[NestWhile[# + 1 &, 1,
    Length[Sow[FirstPosition[t, Prime[#]]]] > 1 &]][[2]][[1]]]]
    (* Peter J. C. Moses, Feb 07 2023 *)

A360485 a(n) = index of the antidiagonal of the Wythoff array (A035513) that includes n.

Original entry on oeis.org

1, 2, 3, 2, 4, 3, 3, 5, 4, 4, 4, 5, 6, 6, 5, 5, 7, 5, 8, 6, 7, 9, 7, 6, 10, 6, 11, 8, 6, 12, 9, 7, 13, 8, 14, 10, 8, 15, 7, 16, 11, 7, 17, 12, 9, 18, 7, 19, 13, 10, 20, 8, 21, 14, 9, 22, 15, 11, 23, 9, 24, 16, 8, 25, 17, 12, 26, 8, 27, 18, 13, 28, 10, 29, 19
Offset: 1

Views

Author

Clark Kimberling, Feb 09 2023

Keywords

Comments

Each m appears exactly m times.

Crossrefs

Programs

  • Mathematica
    W[n_, k_] := Fibonacci[k + 1] Floor[n*GoldenRatio] + (n - 1) Fibonacci[k];
    t = Table[W[n - k + 1, k], {n, 300}, {k, n, 1, -1}];
    Map[#[[1]] &, Most[Reap[NestWhileList[# + 1 &, 1,
    Length[Sow[FirstPosition[t, #]]] > 1 &]][[2]][[1]]]]
    (* Peter J. C. Moses, Feb 08 2023 *)
Showing 1-4 of 4 results.