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 A177880 #22 Aug 31 2020 12:21:22
%S A177880 4,9,12,18,20,25,28,32,36,44,45,49,50,52,60,63,64,68,72,75,76,84,90,
%T A177880 92,96,98,99,100,108,116,117,121,124,126,128,132,140,144,147,148,150,
%U A177880 153,156,160,164,169,171,172,175,180,188,192,196,198,200,204,207
%N A177880 Numbers k such that not all exponents in the prime power factorization of k are in A005836.
%C A177880 1 and products of distinct numbers of the form P^(3^k), k>=0, are not in the sequence.
%H A177880 Amiram Eldar, <a href="/A177880/b177880.txt">Table of n, a(n) for n = 1..10000</a>
%F A177880 Let A(x) be counting function of terms not exceeding x. Then for x tends to infinity, A(x)=C*x+o(x^(0.5+eps), where C=1-Prod{i=p^(3^k)with prime p and k>=0}(1-1/(i^2+i+1)).
%t A177880 Select[Range[200], AnyTrue[FactorInteger[#][[;; , 2]], DigitCount[#1, 3, 2] > 0 &] &] (* _Amiram Eldar_, Aug 31 2020 *)
%o A177880 (Sage) is_A005836 = lambda n: 2 not in n.digits(base=3)
%o A177880 is_A177880 = lambda n: not all(is_A005836(Integer(m)) for p,m in factor(n)) # _D. S. McNeil_, Dec 16 2010
%Y A177880 Cf. A005836.
%K A177880 nonn
%O A177880 1,1
%A A177880 _Vladimir Shevelev_, Dec 15 2010
%E A177880 Extended by _D. S. McNeil_, Dec 16 2010