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.

Showing 1-2 of 2 results.

A354772 For the imaginary quadratic field of discriminant -47, odd primes p such that the Iwasawa lambda invariant lambda_p exceeds 1.

Original entry on oeis.org

3, 17, 157, 1193, 1493, 1511
Offset: 1

Views

Author

N. J. A. Sloane, Jun 26 2022

Keywords

Comments

There are no further terms below 10^7.

Crossrefs

Cf. A239902.

A275118 Split primes p such that prime P lying above p is a Wieferich place of K (with discriminant D_K), for some imaginary quadratic field K of class number 1.

Original entry on oeis.org

5, 11, 13, 181, 1523, 1741, 2521, 19531, 24421, 29789, 76543, 108529, 489061, 880301, 1769069, 6811741
Offset: 1

Views

Author

Felix Fröhlich, Jul 18 2016

Keywords

Crossrefs

Cf. A239902.

Programs

  • Sage
    def is_A275118(k):
        if not Integer(k).is_prime(): return False
        for D in [1, 2, 3, 7, 11, 19, 43, 67, 163]:
            fct = QuadraticField(-D).ideal(k).factor()
            if len(fct)==2:
                pi = fct[1][0].gens_reduced()[0]
                if (pi^(k-1) - 1).valuation(fct[0][0]) > 1: return True
        return False
    print([k for k in range(10^7) if is_A275118(k)])  # Robin Visser, Apr 26 2024

Extensions

a(11)-a(16) from Robin Visser, Apr 26 2024
Showing 1-2 of 2 results.