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A320587 Primes that are not Base-3 deletable primes (written in base 10). 1

%I #44 Dec 07 2018 12:27:09

%S 3,13,31,37,41,43,67,79,97,103,109,113,127,131,139,149,151,157,163,

%T 193,199,211,227,229,239,241,257,271,277,281,283,293,307,311,313,331,

%U 337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,433,439,443

%N Primes that are not Base-3 deletable primes (written in base 10).

%C A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime.

%C Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

%C Complement of all primes and A319596.

%H Robert Price, <a href="/A320587/b320587.txt">Table of n, a(n) for n = 1..906</a>

%t b = 3; d = {};

%t p = Select[Range[2, 10000], PrimeQ[#] &];

%t For[i = 1, i <= Length[p], i++,

%t c = IntegerDigits[p[[i]], b];

%t If[Length[c] == 1, AppendTo[d, p[[i]]]; Continue[]];

%t For[j = 1, j <= Length[c], j++,

%t t = Delete[c, j];

%t If[t[[1]] == 0, Continue[]];

%t If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; Break[]]]]; Complement[Table[Prime[n], {n, PrimePi[Last[d]]}], d] (* _Robert Price_, Dec 06 2018 *)

%Y Cf. A080608, A080603, A096235-A096246.

%K nonn,base,easy

%O 1,1

%A _Robert Price_, Nov 14 2018

%E Added the term 3. As pointed out by Kevin Ryde, there is no need to "seed" the list using base-2 assumptions. - _Robert Price_, Dec 06 2018

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Last modified August 14 23:14 EDT 2024. Contains 375171 sequences. (Running on oeis4.)