1,1

The construction of the array is made in an orthogonal grid with columns and rows.

Along the sloping upper boundary of the array are written the guiding prime numbers, each in a column of its value and in a row of its index. From these leading entries, on downward and leftward running antidiagonal lines the preceding primes are entered. In reverse order and with the due prime gaps, these will fall into the columns of their own value, below the guiding primes on top.

The antidiagonals are the same as the rows of the triangle in A037126.

The rows that begin with 2's end with A256491.

Row n lists all primes of the form A000040(n - k) - k for positive k. - Thomas Scheuerle, May 23 2022

Michael De Vlieger, Table of n, a(n) for n = 1..10701 (rows n = 1..400, flattened)

Michael De Vlieger, Bitmap of 2^(pi(T(n,k)) - 1) for n = 1..1024.

Thomas Scheuerle, The first 1000 rows, a(1 .. 58521) as scatter plot.

Thomas Scheuerle, Lengths of the first 10000 rows as plot against row number.

. 2

. . 3

. 2 . . 5

. . . . . . 7

. . 3 . . . . . . . 11

. 2 . . 5 . . . . . . . 13

. . . . . . . . . . . . . . . . 17

. . 3 . . . . . . . 11 . . . . . . . 19

. 2 . . . . 7 . . . . . . . . . . . . . . . 23

. . . . . . . . . . . . . . . . 17 . . . . . .

. . . . 5 . . . . . . . 13 . . . . . . . . . .

. . . . . . 7 . . . . . . . . . . . . . . . .

. . 3 . . . . . . . 11 . . . . . . . 19 . . . .

. 2 . . 5 . . . . . . . 13 . . . . . . . . . .

. . . . . . . . . . . . . . . . 17 . . . . . .

. . 3 . . . . . . . 11 . . . . . . . . . . . 23

. 2 . . . . 7 . . . . . . . . . . . . . . . .

Table[Select[Array[Prime[#] - (n - #) &, n], And[# > 0, PrimeQ[#]] &], {n, 24}] // Flatten (* Michael De Vlieger, May 25 2022 *)

(* Extract data from the bitmap: set k to number of rows desired, up to 1024 *)

k = 120; Map[Prime /@ Position[#, 0.][[All, 1]] &, ImageData[Import["https://oeis.org/A354271/a354271_2.png"]][[1 ;; k]] ] // Flatten (* Michael De Vlieger, May 25 2022 *)

(MATLAB)

function a = A354271( max_row )

p = primes(max_row*floor(2*max_row*log(max_row)));

a = [];

for r = 1:max_row

row = p(1:r)-(r-1:-1:0);

row = row(isprime(max(row, 0)) > 0);

a = [a row];

end

end % Thomas Scheuerle, May 23 2022

Cf. A000040, A037126, A256491.

Sequence in context: A192141 A092556 A347000 * A344482 A092550 A058977

Adjacent sequences: A354268 A354269 A354270 * A354272 A354273 A354274

nonn,tabf

Tamas Sandor Nagy, May 22 2022

approved