A114007 -id:A114007 - cp's OEIS frontend

A327920 The 16 pure prime dates of each year of the form concatenate(day,month) with month and day also prime numbers.

23, 53, 73, 113, 173, 193, 233, 293, 313, 37, 137, 197, 317, 211, 311, 2311

Offset: 1

Wolfdieter Lang, Oct 08 2019

For the case of the 16, respectively 17, pure prime dates of the form concatenate(month,day) see A327918 (non-leap years) and A327919 (leap years).
Only the three months m = 3, 7, and 11 qualify. The qualifying days are for November (m = 11): d = 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, and for months March and July (m = 3 and 7): d = 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31.
The months m = 3, 7, 11 contribute 9, 4, 3 dates, respectively, adding to 16.

Cf. A055782 (first nine terms), A055783 (first four terms), A114007 (three terms starting with n = 8). A327346 (with d and m also nonprime allowed), A327918, A327919.

Select[Flatten[Table[d*10^IntegerLength[m]+m,{m,{3,7,11}},{d,Prime[ Range[ 11]]}]],PrimeQ] (* Harvey P. Dale, May 24 2022 *)

A114101 Begin with prime(1), then prime(2). After prime(j) write all the primes of the form prime(i) concatenated with prime(j) with i

Original entry on oeis.org

2, 3, 23, 5, 7, 37, 11, 211, 311, 13, 313, 17, 317, 1117, 19, 719, 1319, 23, 223, 523, 1123, 1723, 29, 229, 1129, 31, 331, 1931, 37, 337, 3137, 41, 241, 541, 1741, 2341, 43, 743, 47, 347, 547, 1747, 2347, 53, 353, 1153, 1753, 2953, 4153, 59, 359

Offset: 1

Amarnath Murthy, Nov 20 2005

			11 is followed by 211, 311 (511 and 711 are not primes); then 13.

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

Cf. A114007.

from itertools import islice
from sympy import isprime, nextprime
def agen(): # generator of terms
    p, s = 2, []
    while True:
        yield p; sp = str(p); s.append(sp); p = nextprime(p)
        yield from filter(isprime,  (int("".join(si + sp)) for si in s))
print(list(islice(agen(), 51))) # Michael S. Branicky, Jun 23 2023

More terms from Amy Postell (arp179(AT)psu.edu), Feb 02 2006

Offset changed to 1 by Michael S. Branicky, Jun 23 2023

cp's OEIS Frontend

A327920 The 16 pure prime dates of each year of the form concatenate(day,month) with month and day also prime numbers.

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A114101 Begin with prime(1), then prime(2). After prime(j) write all the primes of the form prime(i) concatenated with prime(j) with i

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