OFFSET
1,1
COMMENTS
Conjecture: every odd number not divisible by 5 is a member.
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..1078
EXAMPLE
2, 23, 239, 23911, 2391113, ... etc. are all prime.
MAPLE
L:=[2]: for n from 1 to 120 do for m from 1 do if isprime(parse(cat("", op(L), m))) and not member(m, L) then L:=[op(L), m]; break fi od od: L[]; # Alec Mihailovs, Aug 14 2005
MATHEMATICA
a[1]=2; a[n_]:=a[n]=Block[{t=1}, While[!PrimeQ[FromDigits@Flatten[IntegerDigits/@Join[Array[a, n-1], {t}]]]||MemberQ[Array[a, n-1], t], t++]; t]; Array[a, 60] (* Giorgos Kalogeropoulos, May 07 2023 *)
PROG
(Python)
from gmpy2 import is_prime
from itertools import count, islice
def agen(): # generator of terms
an, s, aset, mink = 2, "2", {2}, 3
while True:
yield an
an = next(k for k in count(mink, 2) if k not in aset and is_prime(int(s+str(k))))
s += str(an)
aset.add(an)
while mink in aset: mink += 2
print(list(islice(agen(), 60))) # Michael S. Branicky, May 11 2023
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Amarnath Murthy, Aug 12 2005
EXTENSIONS
More terms from Alec Mihailovs (alec(AT)mihailovs.com), Aug 14 2005
Edited by Charles R Greathouse IV, Apr 27 2010
STATUS
approved