cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A159292 Pandigital emirps.

Original entry on oeis.org

10124389567, 10124563789, 10124597683, 10124635897, 10124673859, 10124687359, 10124695783, 10124735689, 10124795683, 10124867359, 10124958673, 10124965387, 10124965783, 10125364897, 10125693847, 10125749863, 10125784639, 10125938467, 10126387549, 10126457893, 10126498573
Offset: 1

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Author

Lekraj Beedassy, Apr 08 2009

Keywords

Comments

There are 413842 11-digit terms. - Jud McCranie, Jul 03 2013 [in light of the comment below, this was independently computed and confirmed to be correct by Michael S. Branicky, Apr 06 2024]
The above statement [by Jud McCranie] is uncertain, as the contributed b-file was wrong (missing terms) from a(436) on. At this point, one has to consider permutations of 10223456789, before coming back, for n > 495, to permutations of 10123456789 starting with 10231.... - M. F. Hasler, Apr 06 2024

Crossrefs

Cf. A006567 (emirps), A050288 (pandigital primes).

Programs

  • PARI
    L=List(); append(N=10123456789, M=Vecsmall([2,3,3]))=forperm(digits(N),p, cmp(p[3..5],M)>0 && break; isprime(P=fromdigits(Vec(p)))&& isprime(fromdigits(Vecrev(p)))&& listput(L, P))
    append(); append(10223456789); #A159292=Set(L) \\ M. F. Hasler, Apr 05 2024
    
  • Python
    from sympy import isprime
    from itertools import count, islice, product
    def emirp(s):
        r = s[::-1]
        return r != s and isprime(int(s)) and isprime(int(r))
    def agen(): # generator of terms
        for d in count(11):
            for f in "1379":
                for m in product("0123456789", repeat=d-2):
                    for e in "1379":
                        t = f + "".join(m) + e
                        if len(set(t)) == 10 and emirp(t):
                            yield int(t)
    print(list(islice(agen(), 100))) # Michael S. Branicky, Apr 09 2024

Formula

Intersection of A006567 and A050288. - M. F. Hasler, Apr 05 2024

Extensions

Erroneous terms corrected and more terms from M. F. Hasler, Apr 05 2024