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 A227289 #6 Aug 01 2019 00:11:02 %S A227289 1,2,4,10,6,177,8,514,500,349,14,4791,16,5949,1623,863,20,2629,22, %T A227289 5113,2043,3211,28,7347,4593,11911,1647,12819,34,27325,36,15755,34527, %U A227289 29319,5459,2797,42,24535,20145,15511,46,26523,48,64895,13335,40769,54,43835,184041 %N A227289 Smallest m such that gcd(A227113(m+1), A227113(m)) = n. %C A227289 A227288(a(n)) = n and A227288(m) <> n for m < a(n). %e A227289 . n | a(n) | A227288(a(n)) = gcd(A227113(a(n)),A227113(a(n)+1)) %e A227289 . ---+--------+--------------- ----------------------------------- %e A227289 . 1 | 1 | 1 = gcd(1,2) %e A227289 . 2 | 2 | 2 = gcd(2,4) %e A227289 . 3 | 4 | 3 = gcd(3,6) %e A227289 . 4 | 10 | 4 = gcd(8,12) %e A227289 . 5 | 6 | 5 = gcd(5,10) %e A227289 . 6 | 177 | 6 = gcd(168,162) %e A227289 . 7 | 8 | 7 = gcd(7,14) %e A227289 . 8 | 514 | 8 = gcd(472,480) %e A227289 . 9 | 500 | 9 = gcd(459,468) %e A227289 . 10 | 349 | 10 = gcd(330,320) %e A227289 . 11 | 14 | 11 = gcd(11,22) %e A227289 . 12 | 4791 | 12 = gcd(4524,4512) %o A227289 (Haskell) %o A227289 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A227289 a227289 = (+ 1) . fromJust . (`elemIndex` a227288_list) %K A227289 nonn %O A227289 1,2 %A A227289 _Reinhard Zumkeller_, Jul 05 2013