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 A308469 #14 Sep 09 2019 07:49:36 %S A308469 1,2,3,5,8,9,10,13,14,15,16,21,22,25,26,27,28,29,30,31,32,33,34,45,46, %T A308469 49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,93, %U A308469 94,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113 %N A308469 a(1) = 1, a(2)=2, a(n) = a(n-1) + gcd(a(n-2), n-2). %C A308469 Apparently, the distinct values of a(n)-n for n > 7 correspond to A190894. - _Rémy Sigrist_, Jul 23 2019 %t A308469 a[1] = 1; a[2] = 2; a[n_] := a[n] = a[n-1] + GCD[a[n-2], n-2]; Array[a, 70] (* _Amiram Eldar_, Aug 01 2019 *) %Y A308469 Cf. A106108, A190894. %K A308469 nonn %O A308469 1,2 %A A308469 _Thomas Kerscher_, May 29 2019