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 A341780 #8 Feb 20 2021 04:28:01
%S A341780 3,15,195,255,483,783,1023,1155,1295,1443,1599,2703,3363,4623,4899,
%T A341780 5183,6399,6723,7395,7743,8463,8835,10815,11235,11663,12099,12543,
%U A341780 15375,16383,16899,17955,18495,20163,24963,25599,26895,27555,31683,33855,35343,36099,37635
%N A341780 Starts of runs of 3 consecutive anti-tau numbers (A046642).
%C A341780 Since the even anti-tau numbers (A268066) are square numbers, all the terms are of the form 4*k^2 - 1, and there cannot be a run of more than 3 consecutive anti-tau numbers.
%H A341780 Amiram Eldar, <a href="/A341780/b341780.txt">Table of n, a(n) for n = 1..10000</a>
%e A341780 3 is a term since 3, 4 and 5 are all anti-tau numbers: gcd(3, tau(3)) = gcd(3, 2) = 1, gcd(4, tau(4)) = gcd(4, 3) = 1 and gcd(5, tau(5)) = gcd(5, 2) = 1.
%t A341780 antiTauQ[n_] := CoprimeQ[n, DivisorSigma[0, n]]; Select[4*Range[100]^2 - 1, AllTrue[# + {0, 1, 2}, antiTauQ] &]
%Y A341780 Subsequence of A000466, A046642 and A341779.
%Y A341780 Cf. A000010, A009191, A268066.
%K A341780 nonn
%O A341780 1,1
%A A341780 _Amiram Eldar_, Feb 19 2021