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.

A346136 a(n) is the number of iterations that n requires to reach 1 under the map n -> A346063(n).

Original entry on oeis.org

0, 1, 2, 2, 3, 3, 1, 4, 1, 4, 3, 3, 4, 3, 2, 4, 4, 5, 2, 3, 9, 11, 8, 6, 10, 12, 6, 7, 2, 8, 4, 3, 6, 4, 10, 7, 2, 7, 4, 9, 4, 5, 4, 1, 8, 7, 6, 11, 2, 73, 5, 12, 5, 6, 1, 5, 2, 4, 34, 7, 5, 5, 2, 51, 7, 2, 5, 3, 5, 5, 3, 15, 6, 5, 2, 4, 10
Offset: 1

Views

Author

Ya-Ping Lu, Jul 05 2021

Keywords

Comments

Conjecture: the sequence is infinite.

Crossrefs

Programs

  • PARI
    f(x) = my(k=x^2-1); while(k>3 && !ispseudoprime(k), k\=2); k;
    a(n) = my(c=0, x=prime(n)); while(x>2, c++; x=f(x)); c; \\ Jinyuan Wang, Jul 15 2022
  • Python
    from sympy import prime, isprime
    for n in range(1, 78):
        m = prime(n); ct = 0
        while m > 2:
            if isprime(m): m = m*m - 1; ct += 1
            else: m //= 2
        print(ct)
    

Extensions

a(1) corrected by Jinyuan Wang, Jul 15 2022