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.

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A354156 Primes p == 1 (mod 4) which are not Lagrange primes.

Original entry on oeis.org

37, 61, 89, 101, 109, 113, 149, 157, 173, 181, 193, 197, 233, 269, 277, 293, 317, 337, 349, 353, 373, 389, 401, 421, 433, 509, 557, 569, 577, 593, 601, 613, 641, 673, 701, 709, 757, 761, 773, 797, 821, 829, 877, 881, 937, 941, 977, 1009, 1013, 1033, 1049, 1061
Offset: 1

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Author

N. J. A. Sloane, May 29 2022, based on Section 18.5 of Cosgrave (2022)

Keywords

References

  • J. B. Cosgrave, A Mersenne-Wieferich Odyssey, Manuscript, May 2022. See Section 18.5.

Crossrefs

This is the complement of A354155 in A002144.

Programs

  • Python
    from itertools import islice
    from sympy import factorial, nextprime
    def agen(): # generator of terms
        p = 5
        while True:
            X = (p-1)//2
            Xf = factorial(X)**2
            if any(pow(factorial(Y), 2, p)+1 == p for Y in range(X-1, 0, -1)):
                yield p
            p = nextprime(p)
            while p%4 != 1:
                p = nextprime(p)
    print(list(islice(agen(), 5))) # Michael S. Branicky, May 30 2022

Extensions

a(26) and beyond from Michael S. Branicky, May 30 2022
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