cp's OEIS Frontend

A278696 Primes p such that every suffix of the ternary (base-3) representation of p is a prime.

%I A278696 #13 Apr 07 2020 23:14:01
%S A278696 2,5,11,23,29,59,83,167,173,191,491,509,569,653,659,677,1481,1487,
%T A278696 1949,2027,2111,4397,4457,4547,4943,5051,5861,6323,6563,13127,13151,
%U A278696 13313,13613,13691,13781,13799,15149,15233,17519,17579,17669,39371,39857,40847,40853,43913,44417,52517,53147,59051
%N A278696 Primes p such that every suffix of the ternary (base-3) representation of p is a prime.
%C A278696 All numbers in the sequence are of one of the forms, base 3:
%C A278696 a. 2
%C A278696 b. 10...02, where there are 0 or more 0's
%C A278696 c. 20...0x, where there are 0 or more 0's, and x is of the form b or c
%C A278696 There is always exactly one 1 in the number, base 3.
%C A278696 All numbers end in a 2, base 3.
%H A278696 Robert Israel, <a href="/A278696/b278696.txt">Table of n, a(n) for n = 1..10000</a>
%e A278696 569 is in the sequence, as 569=210002_3 and its base-3 suffixes are 10002_3=83 and 2_3=2, both of which are prime.
%p A278696 F[1]:= [2]:
%p A278696 for m from 2 to 11 do
%p A278696   F[m]:= [op(F[m-1]),op(select(isprime, [seq(seq(i*3^
%p A278696 (m-1)+x,x=F[m-1]),i=[1,2])]))]
%p A278696 od:
%p A278696 F[11]; # _Robert Israel_, Jan 22 2020
%Y A278696 Cf. A278694.
%K A278696 nonn,base
%O A278696 1,1
%A A278696 _Randy L. Ekl_, Nov 26 2016