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 A125227 #12 Sep 11 2019 08:19:20 %S A125227 1,3,7,9,21,27,49,57,63,81,147,171,189,219,243,301,343,399,441,513, %T A125227 567,657,729,889,903,1029,1083,1197,1323,1533,1539,1701,1971,2107, %U A125227 2187,2359,2401,2667,2709,2793,3087,3249,3591,3969,4161,4401,4599,4617,5103,5913 %N A125227 A014741(n)/6 for n>2. %C A125227 A014741(n) is divisible by 6 for n>2. %C A125227 All powers of 3 are terms. All powers of 7 are terms. The prime divisors of terms of this sequence (for n up to 10^6) in order of their first appearance are 3, 7, 19, 73, 43, 127, 337, 163, 379, 571, 5419, 487, 2593, 439, 1459, 431, 883. %C A125227 The sequence is multiplicative in the sense that if two numbers k and m are terms, then k*m is too. %H A125227 Amiram Eldar, <a href="/A125227/b125227.txt">Table of n, a(n) for n = 3..10000</a> %F A125227 a(n) = A014741(n)/6 = A014945(n-1)/3. - _Max Alekseyev_, Nov 14 2012 %e A125227 a(3) = A014741(3)/6 = 6/6 = 1. %e A125227 a(4) = A014741(4)/6 = 18/6 = 3. %t A125227 Select[Range[3,6000], PowerMod[2,#+1,# ]==2&]/6 %Y A125227 Cf. A014741, A000295, A086787. %K A125227 nonn %O A125227 3,2 %A A125227 _Alexander Adamchuk_, Jan 15 2007