A191304 Records in A132199.

1, 5, 11, 23, 47, 101, 233, 467, 941, 1889, 3779, 7559, 15131, 30323, 60647, 121403, 242807, 486041, 972533, 1945649, 3891467, 7783541, 15567089, 31139561, 62279171, 124559609, 249120239, 498270791, 996541661, 1993083437, 3986167223, 7972334723, 15944673761

Offset: 1

Author

Robert G. Wilson v, Apr 30 2009

Keywords

• nonn

Comments

Except for a(1)=1, log(a(n)) is nearly but not exactly linear. - Ralf Steiner, Aug 18 2017

Links

• Ralf Steiner, Table of n, a(n) for n = 1..171

Crossrefs

Cf. A106108, A132199, A137613.

Programs

Mathematica

Union@ FoldList[Max, Rest@ # - Most@ #] &@ FoldList[#1 + GCD[#2, #1] &, 7, Range[2, 10^7]] (* Michael De Vlieger, Aug 19 2017, after Robert G. Wilson v at A132199 *)

Formula

For all a(n) except a(1)=1 is 5 congruent mod 6, a(n+1) > 2 a(n) and lim_{n->inf} a(n+1)/a(n) = 2. - Ralf Steiner, Aug 18 2017

Extensions

a(23)-a(33) from Ralf Steiner, Aug 18 2017