A375579 Lexicographically earliest sequence of distinct positive integers such that the products of two consecutive terms belong to A055932.

1, 2, 3, 4, 6, 5, 12, 8, 9, 10, 15, 14, 30, 7, 60, 16, 18, 20, 21, 40, 24, 25, 36, 27, 32, 45, 28, 75, 42, 35, 48, 50, 54, 64, 72, 70, 33, 140, 63, 80, 81, 90, 49, 120, 56, 105, 22, 210, 11, 420, 44, 315, 66, 175, 84, 55, 126, 100, 96, 108, 125, 144, 128, 135

Offset: 1

Author

Rémy Sigrist, Aug 19 2024

Keywords

• nonn

Comments

a(n+1) is a multiple of A083720(a(n)).

This sequence has similarities with A175343; here we consider prime factors of consecutive terms, there ones in binary expansions of consecutive terms.

Examples

			The first terms, alongside their prime factors, are:
  n   a(n)  2  3  5  7
  --  ----  -  -  -  -
   1     1
   2     2  X
   3     3     X
   4     4  X
   5     6  X  X
   6     5        X
   7    12  X  X
   8     8  X
   9     9     X
  10    10  X     X
  11    15     X  X
  12    14  X        X
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program

Crossrefs

Cf. A055932, A083720, A175343, A375281, A375615.

Programs

PARI

\\ See Links section.