OFFSET
1,1
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..231
EXAMPLE
313, 727, 11311, etc. are primes.
MATHEMATICA
nxt[{a_, b_}]:=Module[{m=b+2, idn=IntegerDigits[a+1]}, While[!PrimeQ[ FromDigits[ Join[IntegerDigits[m], idn, IntegerDigits[m]]]], m=m+2]; {a+1, m}]; Transpose[NestList[nxt, {1, 3}, 40]][[2]] (* Harvey P. Dale, Sep 26 2012 *)
PROG
(Python)
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
m = 1
for n in count(1):
while not isprime(int(str(m)+str(n)+str(m))):
m += 2
yield m
m += 2
print(list(islice(agen(), 46))) # Michael S. Branicky, Aug 10 2022
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Dec 06 2003
EXTENSIONS
More terms from Ray G. Opao, Nov 18 2004
a(36) and beyond from Michael S. Branicky, Aug 09 2022
STATUS
approved