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 A271468 #14 Apr 09 2016 15:46:06 %S A271468 1,5,10,15,17,20,25,28,30,34,35,37,40,45,50,51,55,56,60,65,68,70,74, %T A271468 75,80,82,84,85,90,95,100,102,105,106,110,111,112,115,119,120,122,125, %U A271468 130,135,136,140,145,148,150,153,155,160,164,165,168,170,175,180 %N A271468 List of indices i such that A269347(3*i) != 3*(i^2 + 1). %C A271468 Equivalently, this sequences is a list of indices i such that A271328(i) != i^2 + 1. %C A271468 If k is in A271328, then k is in this sequence. %C A271468 All multiples of a(k) are in the sequence for k > 1. %H A271468 Peter Kagey, <a href="/A271468/b271468.txt">Table of n, a(n) for n = 1..10000</a> %e A271468 A269347(3*1) = 3 != 3*(1^2 + 1) = 6 so 1 is in the sequence. %e A271468 A269347(3*2) = 15 = 3*(2^2 + 1) so 2 is not in the sequence. %e A271468 A269347(3*3) = 30 = 3*(3^2 + 1) so 3 is not in the sequence. %e A271468 A269347(3*4) = 51 = 3*(4^2 + 1) so 4 is not in the sequence. %e A271468 A269347(3*5) = 84 != 3*(5^2 + 1) = 78 so 5 is in the sequence. %K A271468 nonn %O A271468 1,2 %A A271468 _Peter Kagey_, Apr 08 2016