The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A053810 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A053810

Prime powers of prime numbers.
(history; published version)

#47 by Joerg Arndt at Wed Aug 14 01:53:41 EDT 2024

STATUS

editing

approved

#46 by Joerg Arndt at Wed Aug 14 01:52:56 EDT 2024

COMMENTS

This is to primes (A000040) as A113877 (Semiprimes to semiprime powers) is to semiprimes (A001358). - Jonathan Vos Post, Mar 26 2013; corrected by M. F. Hasler, Nov 06 2023

STATUS

approved

editing

#45 by Joerg Arndt at Wed Aug 14 01:51:56 EDT 2024

STATUS

reviewed

approved

#44 by Michel Marcus at Wed Aug 14 01:50:12 EDT 2024

STATUS

proposed

reviewed

#43 by Chai Wah Wu at Tue Aug 13 22:00:44 EDT 2024

STATUS

editing

proposed

#42 by Chai Wah Wu at Tue Aug 13 22:00:40 EDT 2024

PROG

return kmax # Chai Wah Wu, Aug 13 2024

#41 by Chai Wah Wu at Tue Aug 13 22:00:32 EDT 2024

PROG

(Python)

from sympy import primepi, integer_nthroot, primerange

def A053810(n):

def f(x): return int(n-1+x-sum(primepi(integer_nthroot(x, p)[0]) for p in primerange(x.bit_length())))

kmin, kmax = 1, 2

while f(kmax) >= kmax:

kmax <<= 1

while True:

kmid = kmax+kmin>>1

if f(kmid) < kmid:

kmax = kmid

else:

kmin = kmid

if kmax-kmin <= 1:

break

return kmax # Chai Wah Wu, Aug 13 2024

STATUS

approved

editing

#40 by Michael De Vlieger at Thu Nov 16 08:44:52 EST 2023

STATUS

reviewed

approved

#39 by Michel Marcus at Thu Nov 16 04:03:34 EST 2023

STATUS

proposed

reviewed

#38 by M. F. Hasler at Wed Nov 15 06:52:34 EST 2023

STATUS

editing

proposed