cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A385661 Lexicographically earliest sequence of distinct positive integers that can be partitioned into runs of pairwise coprime integers, the n-th such run having a(n) terms.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 6, 11, 13, 17, 8, 9, 19, 23, 25, 10, 21, 29, 31, 37, 41, 43, 12, 35, 47, 53, 59, 61, 14, 15, 67, 71, 73, 79, 83, 89, 97, 101, 103, 16, 27, 49, 55, 107, 109, 113, 127, 131, 137, 139, 149, 151, 18, 65, 77, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229
Offset: 1

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Author

Rémy Sigrist, Aug 09 2025

Keywords

Comments

This sequence is a permutation of the positive integers as each run starts with the least integer not yet in the sequence.
The prime numbers appear in natural order.

Examples

			The first terms and runs are:
  n   a(n)  n-th run
  --  ----  -----------------------------------------------------------
   0     1  1
   1     2  2, 3
   3     3  4, 5, 7
   6     4  6, 11, 13, 17
  10     5  8, 9, 19, 23, 25
  15     7  10, 21, 29, 31, 37, 41, 43
  22     6  12, 35, 47, 53, 59, 61
  28    11  14, 15, 67, 71, 73, 79, 83, 89, 97, 101, 103
  39    13  16, 27, 49, 55, 107, 109, 113, 127, 131, 137, 139, 149, 151
		

Crossrefs

See A386932 for a similar sequence.
Cf. A076034, A385735 (inverse).

Programs

  • PARI
    \\ See Links section.

Formula

T(n, 1) = 2*n-2 for any n > 1.
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