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.
%I A352774 #11 Apr 04 2022 10:11:05 %S A352774 1,2,5,3,7,11,13,17,19,23,25,29,31,37,9,35,41,27,43,47,49,53,55,59,61, %T A352774 67,15,71,73,65,77,51,79,83,85,89,91,97,33,101,95,39,103,107,109,113, %U A352774 115,119,121,127,21,125,131,57,137,139,133,45,143,149,63,145,151,69,157,155,161,81,163,167 %N A352774 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number that has not appeared that does not share a factor with a(n-2) + a(n-1) or a(n-2)*a(n-1). %C A352774 As a(2) is even, which forces a(3) and a(4) to be odd, all following terms will be odd as the sum of two odd terms is even. Beyond a(5) = 7 all subsequent primes appear in their natural order. %H A352774 Scott R. Shannon, <a href="/A352774/a352774.png">Image of the first 5000 terms</a>. The green line is y = n. %e A352774 a(2) = 5 as a(1) + a(2) = 3, a(1)*a(2) = 2, and 5 is the smallest unused number that does not share a factor with 3 or 2. %Y A352774 Cf. A352768, A352790, A332301, A351001, A349493, A251622. %K A352774 nonn %O A352774 1,2 %A A352774 _Scott R. Shannon_, Apr 02 2022