OFFSET
1,1
COMMENTS
Conjecture: every odd prime is a member.
LINKS
Robert Israel, Table of n, a(n) for n = 1..300
MAPLE
xcat:= proc(a, b) 10^(1+ilog10(b))*a+b end proc:
A[1]:= 5; C:= A[1]:
Cands:= select(isprime, [3, seq(i, i=7..10^6, 2)]):
for n from 2 to 100 do
found:= false;
for i from 1 to nops(Cands) while not found do
x:= Cands[i];
cx:= xcat(C, x);
if isprime(cx) then
found:= true;
C:= cx;
Cands:= subsop(i=NULL, Cands);
A[n]:= x;
fi
od;
if not found then break fi;
od:
seq(A[i], i=1..n-1); # Robert Israel, May 05 2016
MATHEMATICA
L={5}; v=5; While[Length@L < 100, p=3; While[MemberQ[L, p] || CompositeQ[w = v* 10^IntegerLength[p] + p], p = NextPrime[p]]; AppendTo[L, p]; v=w]; L (* Giovanni Resta, May 05 2016 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 06 2003
EXTENSIONS
More terms from Max Alekseyev, Aug 15 2013
STATUS
approved