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

1,1

Comments

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

Links

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

Formula

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

Example

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.

Mathematica

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

Crossrefs

Cf. A005117, A013929, A078144.

Sequence in context: A338628 A323253 A160212 * A187861 A280484 A203335

Adjacent sequences: A188293 A188294 A188295 * A188297 A188298 A188299

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Mar 29 2011

Status

approved