A306992 Lexicographically earliest sequence of distinct positive terms such that the product of two consecutive terms is digitally balanced.

1, 2, 5, 7, 6, 25, 9, 15, 10, 17, 12, 13, 4, 3, 14, 11, 18, 31, 19, 29, 8, 23, 26, 22, 40, 63, 33, 69, 36, 67, 34, 21, 99, 27, 30, 82, 28, 81, 35, 61, 16, 47, 50, 53, 48, 73, 37, 20, 41, 56, 45, 49, 43, 52, 51, 42, 54, 46, 55, 44, 57, 38, 65, 127, 66, 135, 70

Offset: 1

Author

Rémy Sigrist, Mar 18 2019

Keywords

• nonn
• look
• base

Comments

Digitally balanced numbers correspond to A031443.

This sequence has similarities with A269361.

Examples

			The first terms, alongside the binary representation of a(n)*a(n+1), are:
  n   a(n)  bin(a(n)*a(n+1))
  --  ----  ----------------
   1     1                10
   2     2              1010
   3     5            100011
   4     7            101010
   5     6          10010110
   6    25          11100001
   7     9          10000111
   8    15          10010110
   9    10          10101010
  10    17          11001100
  11    12          10011100
  12    13            110100
  13     4              1100
  14     3            101010
  15    14          10011010
  16    11          11000110
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program for A306992

Crossrefs

See A306994 for the additive variant.

Cf. A031443, A269361.

Programs

PARI

See Links section.