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.

User: Katherine E. Stange

Katherine E. Stange's wiki page.

Katherine E. Stange has authored 1 sequences.

A172469 Primes congruent to +/-1 or +/-7 modulo 25.

Original entry on oeis.org

7, 43, 101, 107, 149, 151, 157, 193, 199, 251, 257, 293, 307, 349, 401, 443, 449, 457, 499, 557, 593, 599, 601, 607, 643, 701, 743, 751, 757, 857, 907, 1049, 1051, 1093, 1151, 1193, 1201, 1249, 1301, 1307, 1399, 1451, 1493, 1499, 1543, 1549, 1601, 1607
Offset: 1

Author

Katherine E. Stange, Feb 03 2010

Keywords

Comments

Equivalently, primes p such that the smallest extension of F_p containing the 5th roots of unity also contains the 25th roots of unity.
In this respect, the sequence is the n=5 instance of a family of sequences. For n=3, see A129805, and for n=2, see A002144.
Equivalently, the primes p for which, if p^t = 1 mod 5, then p^t = 1 mod 25.

Programs

  • Python
    from itertools import count, islice
    from sympy import isprime
    def A172469_gen(): # generator of terms
        yield from (7, 43)
        for n in count(50,50):
            for m in (1,7,43,49):
                if isprime(n+m):
                    yield n+m
    A172469_list = list(islice(A172469_gen(),48)) # Chai Wah Wu, Apr 28 2025

Formula

A141927 U A141932 U A141946 U A141941. [From R. J. Mathar, Feb 05 2010]

Extensions

More terms from R. J. Mathar, Feb 05 2010