OFFSET
1,1
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..10000
EXAMPLE
2.4.3.4.5.4.7.4.11 = 2434547411, which is prime. Hence 4 is in the sequence.
MATHEMATICA
v={}; Do[If[PrimeQ[FromDigits[Join[{2}, IntegerDigits[n], {3}, IntegerDigits[n], {5}, IntegerDigits[n], {7}, IntegerDigits[n], {1, 1}]]], v=Append[v, n]], {n, 1000}]; v
Select[Range[660], PrimeQ[FromDigits[Join[{2}, IntegerDigits[ # ], {3}, IntegerDigits[ # ], {5}, IntegerDigits[ # ], {7}, IntegerDigits[ # ], {1, 1}]]] &] (* Stefan Steinerberger, Jun 28 2007 *)
PROG
(Python)
from sympy import isprime
def aupton(terms):
n, alst = 1, []
while len(alst) < terms:
s = str(n)
t = int('2'+s+'3'+s+'5'+s+'7'+s+'11')
if isprime(t): alst.append(n)
n += 1
return alst
print(aupton(55)) # Michael S. Branicky, Apr 18 2021
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Farideh Firoozbakht, Jun 19 2003
EXTENSIONS
Edited by Stefan Steinerberger, Jun 28 2007
Edited by N. J. A. Sloane, Sep 18 2008 at the suggestion of R. J. Mathar
STATUS
approved