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 1-1 of 1 results.

A381702 a(n) is the least k such that A277847(k) = 2*n.

Original entry on oeis.org

2, 6, 11, 14, 19, 22, 53, 31, 137, 38, 43, 46, 101, 81, 59, 62, 67, 71, 149, 79, 83, 86, 181, 94, 197, 103, 107, 121, 229, 118, 977, 127, 131, 134, 139, 142, 293, 151, 617, 158, 163, 166, 1361, 258, 179, 362, 373, 191, 389, 199, 809, 206, 211, 214, 6977, 223, 227, 458, 937, 239, 30977, 1954, 251, 254, 1033, 262
Offset: 1

Views

Author

Aloe Poliszuk, Mar 03 2025

Keywords

Examples

			Table of n, a(n), A277847(a(n)), [row(a(n))] starts (where row(n) is row n of A381348):
  1, 2,  2,  [0,1]
  2, 6,  4,  [0,1,3,4]
  3, 11, 6,  [0,1,3,4,5,9]
  4, 14, 8,  [0,1,2,4,7,8,9,11]
  5, 19, 10, [0,1,4,5,6,7,9,11,16,17]
  6, 22, 12, [0,1,3,4,5,9,11,12,14,15,16,20]
  ...

Crossrefs

Cf. A381348, A277847.

Programs

  • Python
    from math import prod
from sympy import totient, factorint
def A277847(n): return prod(((m:=int(totient(p**e)))>>(~m&m-1).bit_length())+1 for p, e in factorint(n).items())
def a(n):
    n,i = 2*n,1
    while True:
        if A277847(i) == n: return i; i += 1
Showing 1-1 of 1 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.