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 A073760 Smallest unrelated number belonging to a term of this sequence equals four. 2
 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78, 82, 86, 90, 94, 98, 102, 106, 110, 114, 118, 122, 126, 130, 134, 138, 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190, 194, 198, 202, 206, 210, 214, 218, 222, 226, 230 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Essentially the same as A016825. LINKS Tanya Khovanova, Recursive Sequences Index entries for linear recurrences with constant coefficients, signature (2, -1). FORMULA Min{URS[m]}=4, where UNR[m]=Complement[RRS[m], Divisors[m]]. a(n) = 4n+2. - Max Alekseyev, Mar 03 2007 a(n)=8*n-a(n-1), (with a(1)=6) [From Vincenzo Librandi, Aug 08 2010] a(1)=6, a(2)=10, a(n)=2*a(n-1)-a(n-2) [From Harvey P. Dale, Mar 06 2012] EXAMPLE For n=2, a(2)=8*2-6=10; n=3, a(3)=8*3-10=14; n=4, a(4)=8*4-14=18 [From Vincenzo Librandi, Aug 08 2010] MATHEMATICA tn[x_] := Table[w, {w, 1, x}]; di[x_] := Divisors[x]; dr[x_] := Union[di[x], rrs[x]]; rrs[x_] := Flatten[Position[GCD[tn[x], x], 1]]; unr[x_] := Complement[tn[x], dr[x]]; tn[x_] := Table[w, {w, 1, x}] di[x_] := Divisors[x] dr[x_] := Union[di[x], rrs[x]] rrs[x_] := Flatten[Position[GCD[tn[x], x], 1]] nr[x_] := Complement[tn[x], rrs[x]] nd[x_] := Complement[tn[x], di[x]] unr[x_] := Complement[tn[x], dr[x]] Do[s=Min[unr[n]]; If[Equal[s, 4], Print[n]], {n, 1, 1000}] 4*Range[60]+2 (* or *) LinearRecurrence[{2, -1}, {6, 10}, 60] (* Harvey P. Dale, Mar 06 2012 *) CROSSREFS Cf. A045763, A073758, A073759, A016825. Sequence in context: A091577 A115036 A133653 * A136767 A187682 A243709 Adjacent sequences:  A073757 A073758 A073759 * A073761 A073762 A073763 KEYWORD nonn AUTHOR Labos Elemer, Aug 08 2002 STATUS approved

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