A073942 Numbers k such that A002977(k) - A002977(k-1) = 1.

3, 6, 11, 13, 16, 19, 22, 24, 28, 33, 37, 41, 43, 48, 50, 55, 62, 64, 67, 70, 73, 75, 81, 84, 86, 93, 95, 98, 106, 109, 111, 115, 120, 124, 127, 129, 138, 142, 145, 147, 150, 158, 162, 164, 168, 170, 173, 182, 186, 189, 191, 196, 198, 203, 211, 215, 218, 220, 223

Offset: 1

Author

Benoit Cloitre, Nov 20 2002

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Amiram Eldar, Plot of a(n)/n for n = 20000..650000

Crossrefs

Cf. A002977.

Programs

Mathematica

max = 1500; s = Union @ Flatten[NestWhileList[Flatten[{2*# + 1, 3*# + 1}] &, 1, Min[#1] < max &]]; 1 + Position[Differences[Select[s, # <= max &]], 1] // Flatten (* Amiram Eldar, May 07 2022 *)

Formula

Conjecture : a(n) is asymptotic to c*n where c is around 3.8...