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 A363191 #7 May 21 2023 12:56:09
%S A363191 16,4,196,968,8712,437400,85730400,5030690600,264615012500,5239012864,
%T A363191 550886816376,2494017320776852
%N A363191 a(n) is the least start of a run of exactly n consecutive powerful numbers (A001694) that are even, or -1 if no such run exists.
%C A363191 No more terms below 10^18.
%C A363191 At most one of the n even consecutive powerful numbers in the run is a perfect square. - _David A. Corneth_, May 21 2023
%e A363191 a(1) = 16, since 16 = 2^4 is an even powerful number, preceded by an odd powerful number, 9 = 3^2, and followed by an odd powerful number, 25 = 5^2.
%e A363191 a(2) = 4, since 4 = 2^2 and 8 = 2^3 are two consecutive even powerful numbers, preceded by an odd powerful number, 1, and followed by an odd powerful number, 9 = 3^2.
%t A363191 seq[lim_] := Module[{pow = Union[Flatten[Table[i^2*j^3, {j, 1, lim^(1/3)}, {i, 1, Sqrt[lim/j^3]}]]], s = {}, rem, ind}, rem = Mod[pow, 2]; Do[ind = SequencePosition[rem, Join[{1}, Table[0, {k}], {1}], 1]; If[ind == {}, Break[]]; AppendTo[s, pow[[ind[[1, 1]] + 1]]], {k, 1, Infinity}]; s]; seq[10^10]
%Y A363191 Cf. A001694, A062739, A349062, A363189, A363190, A363192.
%K A363191 nonn,more
%O A363191 1,1
%A A363191 _Amiram Eldar_, May 21 2023