%I #17 Jun 01 2021 08:08:31

%S 6,1,3,1,41,19,17,1,81,27,89,3,79,29,1,111,29,13,119,207,21,33,19,413,

%T 49,71,183,223,153,21,261,369,29,319,107,1,273,81,711,507,87,579,401,

%U 7,33,771,477,33,371,91,1559,357,297,9,177,523,77,103,167,199,143,199

%N a(1) = 6; a(n) = smallest number such that the juxtaposition a(1)a(2)...a(n) is a prime.

%H Michael S. Branicky, <a href="/A069608/b069608.txt">Table of n, a(n) for n = 1..303</a>

%e a(5) = 41 and the number 613141 is a prime.

%t a[1] = 6; a[n_] := a[n] = Block[{k = 1, c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ !PrimeQ[ FromDigits @ Flatten @ Append[c, IntegerDigits[k]]], k += 2]; k]; Table[ a[n], {n, 63}] (* _Robert G. Wilson v_, Aug 05 2005 *)

%o (Python)

%o from sympy import isprime

%o def aupton(terms):

%o alst, astr = [6], "6"

%o for n in range(2, terms+1):

%o an = 1

%o while not isprime(int(astr+str(an))): an += 1

%o alst, astr = alst + [an], astr + str(an)

%o return alst

%o print(aupton(62)) # _Michael S. Branicky_, Jun 01 2021

%Y Cf. A069602, A069604, A046256, A074342, A092528, A069603, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A111525.

%K nonn,base

%O 1,1

%A _Amarnath Murthy_, Mar 26 2002

%E More terms from _Jason Earls_, Jun 13 2002