A377367 - OEIS

A377367

Rectangular array by antidiagonals: R(m,n) = least k such that 2n*prime(m)^k + 1 is prime.

1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 2, 4, 1, 1, 6, 4, 1, 1, 1, 10, 1, 1, 3, 1, 3, 1, 1, 2, 1, 1, 14, 1, 1, 2, 2, 3, 8, 3, 2, 1, 1, 1, 2, 1, 3, 3, 1, 11, 1, 1, 1, 1, 4, 2, 1, 1, 1, 2, 2, 4, 6, 5, 4, 1, 1

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..78.

EXAMPLE

Corner:

1 1 1 2 1 1 1 3 2 1 1 1 1 3 2

1 2 1 1 2 1 1 2 3 1 4 2 1 2 1

1 1 1 4 1 1 3 3 1 1 1 8 1 3 11

1 1 1 10 2 8 1 2 3 2 1 1 1 1 8

1 1 1 1 3 11 2 1 2 4 1 8 1 1 1

6 1 1 2 1 4 1 13 2 1 1 2 3 3 1

3 14 1 1 6 1 1 3 1 1 8 1 4 2 3

1 1 1 5 4 7 1 14 2 1 2 1 2 1 6

1 1 4 1 3 2 1 2 3 2 5 1 6 1 2

4 1 1 2 2 1 3 5 1 5 1 1 1 1 4

1 1 2 3 1 2 3 2 3 1 9 1 3 1 1

1 3 2 2 4 1 1 7 1 11 4 1 1 10 3

1 1 2 3 3 1 1 3 1 1 1 2 1 1 2

2 1 2 3 1 8 1 1 1 2 3 1 1 2 1

1 16 1 4 11 1 4 3 3 2 18 1 2 4 2

MATHEMATICA

f[m_, n_, k_] := 2 n*Prime[m]^k + 1;

s[m_, n_] := Select[Range[20], PrimeQ[f[m, n, #]] &, 1]

u[m_] := Flatten[Table[s[m, n], {n, 1, 60}]]

Column[Table[Take[u[m], 16], {m, 2, 16}]]

r[m_] := Take[u[m], 12];

w[m_, n_] := r[m][[n]];

Table[w[m, n], {m, 1, 16}, {n, 1, 12}] (* array *)

Table[w[n - k + 1, k], {n, 12}, {k, n, 1, -1}] // Flatten (* sequence *)

CROSSREFS

Cf. A000040, A377366.

Sequence in context: A329041 A238744 A030421 * A085021 A060209 A037830

Adjacent sequences: A377364 A377365 A377366 * A377377 A377379 A377380

KEYWORD

nonn,tabl,new

AUTHOR

Clark Kimberling, Oct 31 2024

STATUS

approved