A188296 Central element of a series of 5 successive nonsquarefree numbers.

846, 1682, 2890, 3626, 5048, 10926, 14750, 15850, 17406, 19942, 22022, 22023, 22626, 23274, 24649, 24650, 25774, 29350, 30250, 30925, 30926, 33174, 36702, 37250, 38726, 39446, 40474, 45374, 47674, 47675, 47726, 47826, 48374, 49490, 54586, 55026, 55449, 55450, 57122, 57123, 58474, 58850

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Mar 29 2011

Keywords

• nonn

Comments

Each of a(n), a(n)-1, a(n)-2, a(n)+1, a(n)+2 has at least one square divisor.

Examples

			846 = 2*3^2*47, 846 - 1 = 5*13^2, 846 - 2 = 2^2*211, 846 + 1 = 7*11^2, 846 + 2 = 2^4*53.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A005117, A013929, A078144.

Programs

Mathematica

Select[Range[1,100000],!SquareFreeQ[#] &&!SquareFreeQ[#-1] &&!SquareFreeQ[#+1] &&!SquareFreeQ[#-2] &&!SquareFreeQ[#+2]&]

Formula

a(n) = A078144(n) + 2. - Amiram Eldar, Feb 09 2021