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A151768 Complement of A071786. 2

%I #7 Aug 06 2017 21:16:58

%S 19,23,29,41,43,46,47,53,57,58,59,61,67,69,82,83,86,87,89,94,103,109,

%T 115,116,122,123,127,129,137,138,139,141,159,161,163,171,173,174,177,

%U 178,183,193,197,201,203,205,206,207,209,211,215,218,223,227,229,230

%N Complement of A071786.

%C A number n > 1 is in the sequence if and only if n/A004086(p) is in the sequence for all primes p with A004086(p) dividing n. [_Hagen von Eitzen_, Jun 23 2009]

%C A076056 is a subsequence. [_Reinhard Zumkeller_, Jul 06 2009]

%p read("transforms") ; tdpr := proc(nd) local p,n ; p := [] ; for n from 1 do if ithprime(n) > 10^nd then break; else p := [op(p),digrev(ithprime(n))] ; fi; od: sort(p) ; end: A071786 := proc(L,nd) local tmp,tmp2,j,k,i ; tmp := [] ; for j from 0 do if op(1,L)^j > 10^nd then break; fi; tmp := [op(tmp),op(1,L)^j] ; od: for i from 2 to nops(L) do tmp2 := {} ; for k from 1 to nops(tmp) do for j from 0 do if op(k,tmp)*op(i,L)^j > 10^nd then break; fi; tmp2 := tmp2 union { op(k,tmp)*op(i,L)^j} ; od: od: tmp := convert(tmp2,list) ; od: tmp ; end: maxp10 := 3 : L := tdpr(maxp10) : a151768c := A071786(L,maxp10) : for n from 1 to 10^maxp10 do if not n in a151768c then printf("%d,",n) ; fi; od: # _R. J. Mathar_, Jun 24 2009

%o (PARI) A=Set([]);for(n=2,300,ok=0;fordiv(n,d,if(!setsearch(A,d)&&isprime(rev(n/d)),ok=1;break));if(!ok,print1(n,",");A=setunion(A,Set([n])))) \\ _Hagen von Eitzen_, Jun 23 2009

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Jun 22 2009

%E More terms from _Hagen von Eitzen_ and _R. J. Mathar_, Jun 23 2009

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)