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 A212166 #20 Sep 08 2024 15:40:33
%S A212166 1,2,3,5,7,11,12,13,17,18,19,20,23,28,29,31,36,37,41,43,44,45,47,50,
%T A212166 52,53,59,61,63,67,68,71,73,75,76,79,83,89,92,97,98,99,100,101,103,
%U A212166 107,109,113,116,117,120,124,127,131,137,139,147,148,149,151,153
%N A212166 Numbers k such that the maximum exponent in its prime factorization equals the number of positive exponents (A051903(k) = A001221(k)).
%D A212166 M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 844.
%H A212166 Reinhard Zumkeller, <a href="/A212166/b212166.txt">Table of n, a(n) for n = 1..10000</a>
%H A212166 M. Abramowitz and I. A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
%H A212166 Primefan, <a href="http://primefan.tripod.com/500factored.html">The First 2500 Integers Factored</a> (first of 5 pages).
%F A212166 A225230(a(n)) = 0; A050326(a(n)) = 1. - _Reinhard Zumkeller_, May 03 2013
%e A212166 36 = 2^2*3^2 has 2 positive exponents in its prime factorization. The maximal exponent in its prime factorization is also 2. Therefore, 36 belongs to this sequence.
%t A212166 okQ[n_] := Module[{f = Transpose[FactorInteger[n]][[2]]}, Max[f] == Length[f]]; Select[Range[424], okQ] (* _T. D. Noe_, May 24 2012 *)
%o A212166 (Haskell)
%o A212166 import Data.List (elemIndices)
%o A212166 a212166 n = a212166_list !! (n-1)
%o A212166 a212166_list = map (+ 1) $ elemIndices 0 a225230_list
%o A212166 -- _Reinhard Zumkeller_, May 03 2013
%o A212166 (PARI) is(k) = {my(e = factor(k)[, 2]); !(#e) || vecmax(e) == #e;} \\ _Amiram Eldar_, Sep 08 2024
%Y A212166 Includes subsequences A000040, A006939, A138534, A181555, A181825.
%Y A212166 See also A212164, A212165, A212167, A212168.
%Y A212166 Cf. A001221, A050326, A051903, A188654 (complement), A225230.
%K A212166 nonn,easy
%O A212166 1,2
%A A212166 _Matthew Vandermast_, May 22 2012