A086040 Prime p concatenated with next 4 primes is also prime.

7, 47, 53, 67, 97, 101, 149, 401, 431, 479, 487, 757, 827, 887, 1061, 1171, 1409, 1429, 1543, 1721, 1789, 1811, 1889, 1987, 2099, 2113, 2137, 2273, 2689, 2719, 2857, 3203, 3571, 3613, 3623, 3761, 3853, 3917, 3929, 4007, 4217, 4441, 4943, 5039, 5209, 5281, 5449

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Example

a(1) = 7 because 7, 11, 13, 17 and 19 concatenated together yield 711131719, which is prime.

Prog

(Python)
from itertools import islice
from sympy import isprime, nextprime
def agen(): # generator of terms
    plst = [2, 3, 5, 7, 11]
    slst = list(map(str, plst))
    while True:
        if isprime(int("".join(slst))):
            yield plst[0]
        plst = plst[1:] + [nextprime(plst[-1])]
        slst = slst[1:] + [str(plst[-1])]
print(list(islice(agen(), 50))) # Michael S. Branicky, Jan 26 2023

Crossrefs

Cf. A030459, A030468, A030472, A086041.

Sequence in context: A036944 A068640 A089725 * A009241 A263920 A124837

Adjacent sequences: A086037 A086038 A086039 * A086041 A086042 A086043

Keyword

base,nonn

Author

Chuck Seggelin (barkeep(AT)plastereddragon.com), Jul 07 2003

Extensions

Offset corrected by Arkadiusz Wesolowski, May 10 2012

a(15) and beyond from Michael S. Branicky, Jan 26 2023

Status

approved