A075648 Left side of the triangle A075652.

1, 2, 3, 7, 8, 14, 22, 31, 40, 60, 82, 83, 108, 162, 205, 221, 222, 342, 379, 399, 421, 508, 597, 669, 718, 894, 947, 727, 1183, 1300, 1361, 1517, 1551, 1754, 1823, 1999, 2288, 2548, 2625, 2821, 3142, 3350, 3519, 3995, 2479, 4320, 4321, 2081, 4660, 5409, 5054

Offset

1,2

Comments

From Christian Wolird, Jul 22 2026: (Start)

A growth rate of O(n^3 / log n) is indicated (though not proven) from a suitable probabilistic approximation.

The sequence is not strictly increasing: a(28) = 727 < 947 = a(27).

Consecutive terms appear surprisingly far into the sequence. For example, a(14514) = 71887645623 and a(14513) = 71887645622.

The frontier terms of the sequence oddly split into two distinct bands around the 15000th term. (End)

Links

Christian Wolird, Table of n, a(n) for n = 1..16000 (terms 1..260 from Andrei Zabolotskii)

GitHub, Code for generating this sequence.

Example

a(4) = 7 and not 5 as 9 has already occurred in the previous row.

Crossrefs

Cf. A075649, A075650, A075651, A075652.

Sequence in context: A199971 A033082 A084406 * A071527 A307328 A097095

Adjacent sequences: A075645 A075646 A075647 * A075649 A075650 A075651

Keyword

nonn,look,changed

Author

Amarnath Murthy, Oct 01 2002

Extensions

More terms from David Wasserman, Jan 22 2005

New name from Ivan Neretin, Nov 09 2016

Status

approved