The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A085902 a(0) = 2, a(n) is the smallest squarefree number > a(n-1) such that the sum a(n) + a(i) for all i = 1 to (n-1) is squarefree. Or, sum of any two terms is a squarefree number. 4
 2, 3, 11, 19, 55, 59, 83, 111, 127, 155, 163, 199, 203, 219, 263, 299, 307, 311, 371, 383, 399, 455, 515, 803, 883, 919, 983, 1063, 1499, 1559, 1927, 2019, 2063, 2183, 2215, 2271, 2359, 2503, 2703, 2755, 2999, 3459, 3899, 3927, 4271, 4303, 4411, 4519, 4559 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS It can easily be proved that a(n) == 3 (mod 4) for all n > 2. LINKS Amiram Eldar, Table of n, a(n) for n = 0..500 MATHEMATICA a[0] = 2; a[n_] := a[n] = Module[{t = Array[a, n, 0], k = a[n - 1] + 1}, While[! SquareFreeQ[k] || AnyTrue[t, ! SquareFreeQ[k + #] &], k++]; k]; Array[a, 100, 0] (* Amiram Eldar, Aug 21 2023 *) CROSSREFS Cf. A005117, A077224, A077225, A080793. Sequence in context: A051101 A045339 A051091 * A051083 A051097 A214773 Adjacent sequences: A085899 A085900 A085901 * A085903 A085904 A085905 KEYWORD nonn AUTHOR Amarnath Murthy, Jul 09 2003 EXTENSIONS More terms from Ray Chandler, Sep 13 2003 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 11 07:17 EST 2023. Contains 367717 sequences. (Running on oeis4.)