A321128 -id:A321128 - cp's OEIS frontend

A320938 Inverse to A321128.

10, 5, 1, 2, 7, 3, 8, 4, 9, 6, 32, 11, 33, 12, 36, 38, 41, 13, 43, 14, 97, 48, 49, 15, 51, 52, 53, 34, 56, 16, 57, 17, 98, 50, 58, 59, 60, 18, 61, 35, 62, 19, 63, 20, 64, 65, 66, 21, 67, 37, 69, 39, 70, 22, 71, 72, 73, 40, 74, 23, 75, 24, 99, 42, 76, 77, 78

Offset: 0

Rémy Sigrist, Oct 28 2018

			A321128(42) = 63, hence a(63) = 42.

Rémy Sigrist, Table of n, a(n) for n = 0..9999

Cf. A321128.

A330384 Single-digit numbers in order of appearance in decimal expansions of composite numbers, followed by two-digit numbers in order of appearance, then three-digit numbers and so forth.

Original entry on oeis.org

4, 6, 8, 9, 1, 0, 2, 5, 7, 3, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86

Offset: 1

David Williams, Dec 12 2019

			From _Rémy Sigrist_, Dec 24 2019: (Start)
The first terms, alongside the corresponding composite numbers, are:
  n   a(n)  Composite
  --  ----  ---------
   1     4          4
   2     6          6
   3     8          8
   4     9          9
   5     1         10
   6     0         10
   7     2         12
   8     5         15
   9     7         27
  10     3         30
  11    10         10
  12    12         12
  13    14         14
  ...
  79    99         99
  80    11        110
  81    17        117
  82    19        119
  83    23        123
(End)

Rémy Sigrist, Table of n, a(n) for n = 1..11000
Rémy Sigrist, Colored scatterplot of the first 110000 terms (red pixels indicate terms that are prime)
Rémy Sigrist, PARI program for A330384

Cf. A002808, A321043, A321128.

PARI
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More terms from Rémy Sigrist, Dec 24 2019

cp's OEIS Frontend

A320938 Inverse to A321128.

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