The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A363597 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A363597

Union of prime powers and numbers that are not squarefree.
(history; published version)

#15 by Joerg Arndt at Sat Aug 03 01:52:53 EDT 2024

STATUS

reviewed

approved

#14 by Michel Marcus at Sat Aug 03 00:57:34 EDT 2024

STATUS

proposed

reviewed

#13 by Chai Wah Wu at Fri Aug 02 20:18:20 EDT 2024

STATUS

editing

proposed

#12 by Chai Wah Wu at Fri Aug 02 20:18:11 EDT 2024

PROG

return m # Chai Wah Wu, Aug 02 2024

#11 by Chai Wah Wu at Fri Aug 02 20:18:00 EDT 2024

PROG

(Python)

from math import isqrt

from sympy import mobius, primepi

def A363597(n):

if n==1: return 1

def f(x): return n-1+sum(mobius(k)*(x//k**2) for k in range(1, isqrt(x)+1))-primepi(x)

m, k = n-1, f(n-1)

while m != k:

m, k = k, f(k)

return m # Chai Wah Wu, Aug 02 2024

STATUS

approved

editing

#10 by OEIS Server at Thu Aug 24 10:22:41 EDT 2023

LINKS

Michael De Vlieger, <a href="/A363597/b363597_1.txt">Table of n, a(n) for n = 1..10000</a>

#9 by N. J. A. Sloane at Thu Aug 24 10:22:41 EDT 2023

STATUS

proposed

approved

Discussion

Thu Aug 24

10:22

OEIS Server: Installed first b-file as b363597.txt.

#8 by Michel Marcus at Thu Aug 24 10:18:11 EDT 2023

STATUS

editing

proposed

#7 by Michel Marcus at Thu Aug 24 10:18:06 EDT 2023

PROG

(PARI) isok(k) = (k==1) || isprimepower(k) || !issquarefree(k); \\ Michel Marcus, Aug 24 2023

STATUS

proposed

editing

#6 by Michael De Vlieger at Tue Aug 22 20:44:19 EDT 2023

STATUS

editing

proposed