This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
2, 23, 239, 23911, 2391113, ... etc. are all prime.
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
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 *)
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
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