cp's OEIS Frontend

A370202 a(n) = a(n-3) + a(n-2) + gcd(a(n-2), a(n-1)) with a(1) = a(2) = a(3) = 1.

%I A370202 #24 Mar 01 2024 15:55:19
%S A370202 1,1,1,3,3,7,7,17,15,25,37,41,63,79,105,143,185,249,329,435,579,767,
%T A370202 1015,1347,1783,2363,3131,4147,5495,7279,9643,12775,16923,22419,29701,
%U A370202 39343,52121,69045,91465,121171,160511,212637,281683,373149,494321,654833,867471
%N A370202 a(n) = a(n-3) + a(n-2) + gcd(a(n-2), a(n-1)) with a(1) = a(2) = a(3) = 1.
%C A370202 The ratio between consecutive terms (a(n)/a(n-1)) appears to approach the plastic constant A060006.
%H A370202 Eli Jaffe, <a href="/A370202/b370202.txt">Table of n, a(n) for n = 1..1000</a>
%o A370202 (Python)
%o A370202 from math import gcd
%o A370202 def terms(n):
%o A370202   nums = [1,1,1]
%o A370202   for i in range(n-3):
%o A370202     new_num = nums[i] + nums[i+1] + gcd(nums[i+1], nums[i+2])
%o A370202     nums.append(new_num)
%o A370202   return nums
%Y A370202 Cf. A060006, A083658.
%K A370202 nonn,easy
%O A370202 1,4
%A A370202 _Eli Jaffe_, Feb 11 2024