A375030 Irregular triangle T(n, k), n > 0, k = 1..A373797(n), read by rows; the n-th row corresponds to the lexicographically earliest sequence S of A373797(n) distinct integers in the range 1..n such that for any prime number p, any run of consecutive multiples of p in S has length exactly 2.

1, 1, 1, 1, 2, 4, 1, 2, 4, 1, 2, 6, 3, 1, 2, 6, 3, 1, 2, 4, 3, 6, 8, 1, 2, 4, 3, 6, 8, 1, 2, 4, 3, 9, 5, 10, 8, 1, 2, 4, 3, 9, 5, 10, 8, 1, 2, 4, 3, 6, 8, 5, 10, 12, 9, 1, 2, 4, 3, 6, 8, 5, 10, 12, 9, 1, 2, 4, 3, 6, 10, 5, 7, 14, 12, 9, 1, 2, 4, 3, 6, 8, 5, 15, 12, 14, 7

Offset

1,5

Links

Rémy Sigrist, Table of n, a(n) for n = 1..386 (rows for n = 1..31 flattened)

Rémy Sigrist, PARI program.

Peter Luschny, Maple program.

Example

Triangle T(n, k) begins:
    1;
    1;
    1;
    1, 2, 4;
    1, 2, 4;
    1, 2, 6, 3;
    1, 2, 6, 3;
    1, 2, 4, 3, 6, 8;
    1, 2, 4, 3, 6, 8;
    1, 2, 4, 3, 9, 5, 10, 8;
    1, 2, 4, 3, 9, 5, 10, 8;
    1, 2, 4, 3, 6, 8, 5, 10, 12, 9;
    1, 2, 4, 3, 6, 8, 5, 10, 12, 9;
    1, 2, 4, 3, 6, 10, 5, 7, 14, 12, 9;
    1, 2, 4, 3, 6, 8, 5, 15, 12, 14, 7;
    1, 2, 4, 3, 6, 8, 5, 10, 12, 9, 7, 14, 16;
    1, 2, 4, 3, 6, 8, 5, 10, 12, 9, 7, 14, 16;
    1, 2, 4, 3, 6, 8, 5, 15, 9, 16, 14, 7, 12, 18;
    1, 2, 4, 3, 6, 8, 5, 15, 9, 16, 14, 7, 12, 18;
    ...

Maple

# See Links section.

Prog

(PARI) \\ See Links section.

Crossrefs

Cf. A280864, A373797.

Sequence in context: A124911 A132954 A069705 * A106645 A115314 A358431

Adjacent sequences: A375027 A375028 A375029 * A375031 A375032 A375033

Keyword

nonn,tabf

Author

Rémy Sigrist at the suggestion of Peter Luschny, Jul 28 2024

Status

approved