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A046735 Nontrivial (i.e., having no nontrivial factors with this property) integers which do not divide any terms of A000213. 4
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

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

David W. Wilson

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 November 23 09:54 EST 2017. Contains 295116 sequences.