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A083756
Beginning with 5, rearrangement of odd primes such that every concatenation beginning with the first term is a prime.
2
5, 3, 23, 13, 17, 19, 11, 31, 47, 109, 89, 571, 53, 271, 149, 151, 101, 409, 173, 241, 587, 337, 1091, 1303, 251, 457, 431, 373, 947, 1447, 2153, 577, 419, 463, 797, 349, 1019, 1063, 557, 619, 2549, 2113, 3257, 331, 383, 1201, 227, 1033, 2333, 3253, 1061, 7
OFFSET
1,1
COMMENTS
Conjecture: every odd prime is a member.
LINKS
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
Cf. A083757.
Sequence in context: A303634 A069607 A128366 * A283507 A290074 A146317
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