|
%I #26 Feb 09 2021 02:49:30
%S 217073,671349,826827,1092750,1092751,1427373,2097051,2779373,3112822,
%T 3306447,3597726,3994823,4063777,4442877,4630547,4842477,5436378,
%U 5479622,5610647,5634125,6315022,6474223,6626322,6677867,7128474,7216621,7216622,7295451,7507926
%N Central element of a series of 7 successive nonsquarefree numbers.
%C Each of a(n), a(n)-1, a(n)-2, a(n)-3, a(n)+1, a(n)+2, a(n)+3 has at least one square divisor.
%H Amiram Eldar, <a href="/A188347/b188347.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A077640(n) + 3. - _Amiram Eldar_, Feb 09 2021
%e 217073=17*113^2, 217073-1=2^4*13567, 217073-2=3^2*89*271, 217073-3=2*5*7^2*443, 217073+1=2*3*11^2*13*23, 217073+2=5^2*19*457, 217073+3=2^2*54269.
%t Select[Range[200000,5000000], !SquareFreeQ[#] &&!SquareFreeQ[#-1] &&!SquareFreeQ[#+1] &&!SquareFreeQ[#-2] &&!SquareFreeQ[#+2] &&!SquareFreeQ[#-3] &&!SquareFreeQ[#+3]&]
%Y Cf. A005117, A013929, A077640, A188296.
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Mar 29 2011
%E More terms from _Carl Najafi_, Aug 22 2011
|
