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 A046735 Nontrivial (i.e., having no nontrivial factors with this property) integers which do not divide any terms of A000213. 5
 2, 27, 91, 103, 163, 199, 203, 221, 247, 305, 371, 377, 397, 421, 551, 559, 757, 779, 883, 991, 1021, 1079, 1087, 1123, 1189, 1199, 1237, 1351, 1521, 1543, 1567, 1609, 1651, 1753, 1769, 1799, 1807, 1873, 1883, 1919, 2009, 2071, 2261, 2539 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..1275 MAPLE nd:= proc(p) local a, b, c, r, R;    a:= 1; b:= 1; c:= 1; R[1, 1, 1]:= true;    do      r:= a+b+c mod p;      if r = 0 then return false fi;      a:= b; b:= c; c:= r;      if assigned(R[a, b, c]) or nops({a, b, c})=1          then return true          else R[a, b, c]:= true        fi;    od end proc: N:= 10^4: # to get all terms <= N V:= Vector(N): Res:= NULL: for n from 1 to N do   if V[n] = 0 then     if nd(n) then Res:= Res, n; V[[seq(k*n, k=2..floor(N/n))]]:= 1; fi   fi; od: Res; # Robert Israel, Feb 26 2017 MATHEMATICA nondivisor[n_] := Module[{a = 1, b = 1, c = 1, t}, For[i = 1, i <= n^2, i++, t = Mod[a+b+c, n]; If[t != 0, a = b; b = c; c = t, Return[False]]; If[c == 1 && b == 1 && a == 1, Return[True]]]]; okQ[n_] := Do[If[nondivisor[d], Return[n == d]], {d, Divisors[n]}]; Select[Range[3000], okQ] (* Jean-François Alcover, Mar 05 2019, from PARI *) PROG (PARI) nondivisor(n)=my(a=1, b=1, c=1, t); for(i=1, n^2, t=(a+b+c)%n; if(t, a=b; b=c; c=t, return(0)); if(c==1&&b==1&&a==1, return(1))) is(n)=fordiv(n, d, if(nondivisor(d), return(n==d))); 0 \\ Charles R Greathouse IV, Aug 29 2012 CROSSREFS Sequence in context: A273844 A294678 A206585 * A038625 A280089 A041801 Adjacent sequences:  A046732 A046733 A046734 * A046736 A046737 A046738 KEYWORD nonn AUTHOR EXTENSIONS Definition corrected by Henry Ayoola (henry.ayoola(AT)googlemail.com), Feb 03 2009 a(1) added by Charles R Greathouse IV, Aug 29 2012 STATUS approved

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Last modified May 12 05:25 EDT 2021. Contains 343811 sequences. (Running on oeis4.)