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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A338763 Let L_1 = (1, 2, ...); for any n > 0, let M_n = Min_{k > 0} L_n(k) + L_n(k+1) and K_n = Min_{ k | L_n(k) + L_n(k+1) = M_n }, L_{n+1} is obtained by replacing the two terms L_n(K_n) and L_n(K_n+1) by M_n in L_n; a(n) = M_n.

Original entry on oeis.org

3, 6, 9, 13, 15, 17, 21, 25, 28, 29, 33, 37, 38, 41, 45, 49, 53, 54, 57, 61, 65, 66, 69, 70, 73, 77, 81, 85, 86, 89, 93, 97, 101, 102, 105, 109, 113, 117, 118, 120, 121, 125, 129, 133, 134, 137, 141, 145, 149, 150, 153, 156, 157, 161, 165, 166, 169, 173, 177
Offset: 1

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Author

Rémy Sigrist, Nov 07 2020

Keywords

Comments

In other words, we start with the natural numbers and repeatedly replace the leftmost pair of consecutive terms with minimal sum by its sum; a(n) corresponds to the sum at n-th step.
This sequence is weakly increasing, and tends to infinity (as for any m > 0, there are only finitely many runs of two or more consecutive integers with a sum < m).

Examples

			The first terms, alongside L_n, are:
  n   a(n)  L_n
  --  ----  ----------------------------------------------------------
   1     3  { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, ... }
   2     6  {   3,  3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, ... }
   3     9  {      6,  4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, ... }
   4    13  {      6,    9,  6, 7, 8, 9, 10, 11, 12, 13, 14, 15, ... }
   5    15  {      6,    9,   13,  8, 9, 10, 11, 12, 13, 14, 15, ... }
   6    17  {         15,     13,  8, 9, 10, 11, 12, 13, 14, 15, ... }
   7    21  {         15,     13,   17,  10, 11, 12, 13, 14, 15, ... }
   8    25  {         15,     13,   17,    21,   12, 13, 14, 15, ... }
   9    28  {         15,     13,   17,    21,     25,   14, 15, ... }
  10    29  {             28,       17,    21,     25,   14, 15, ... }
		

Crossrefs

Programs

  • PARI
    See Links section.

Formula

a(n) <= a(n+1).
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