The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A101226 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A101226

Numbers formed by the fourth nesting of pi(10^n).
(history; published version)

#16 by Peter Luschny at Sat Jun 29 07:16:50 EDT 2024

STATUS

reviewed

approved

#15 by Stefano Spezia at Sat Jun 29 06:23:52 EDT 2024

STATUS

proposed

reviewed

#14 by Michel Marcus at Sat Jun 29 06:16:46 EDT 2024

STATUS

editing

proposed

#13 by Michel Marcus at Sat Jun 29 06:16:43 EDT 2024

PROG

(PARI) nestpi(n, m) = { localmy(x, y, z); for(x=1, n, z=10^x; for(y=1, m, z=piprimepi(z)); print1(z", ")) } pi(n) = \pi(n) Prime count function { local(c, x); c=0; forprime(x=1, n, c++); return\ try call nestpi(c11, 4) }

STATUS

proposed

editing

#12 by Amiram Eldar at Sat Jun 29 03:55:17 EDT 2024

STATUS

editing

proposed

#11 by Amiram Eldar at Sat Jun 29 03:32:02 EDT 2024

FORMULA

a(n) = A00720A000720(A101225(n)). - Amiram Eldar, Jun 29 2024

CROSSREFS

Cf. A00720, A000720, A006880, A096359, A101225.

#10 by Amiram Eldar at Sat Jun 29 03:31:24 EDT 2024

LINKS

Kim Walisch, <a href="https://github.com/kimwalisch/primecount">Fast C++ prime counting function implementation (primecount)</a>.

FORMULA

a(n) = A00720(A101225(n)). - Amiram Eldar, Jun 29 2024

CROSSREFS

Cf. A00720, A006880, A096359, A101225.

EXTENSIONS

a(14)-a(24) from _using Kim Walisch's primecount added by _Amiram Eldar_, Jun 29 2024

#9 by Amiram Eldar at Sat Jun 29 03:30:38 EDT 2024

FORMULA

a(n) = pi(pi(pi(pi(10^n)))) where pi(x) is the number of primes LE <= x.

#8 by Amiram Eldar at Sat Jun 29 03:28:45 EDT 2024

EXTENSIONS

a(10)-a(1413) from Robert G. Wilson v, Dec 21 2004

a(14)-a(24) from Amiram Eldar, Jun 29 2024

#7 by Amiram Eldar at Sat Jun 29 03:27:22 EDT 2024

DATA

0, 2, 5, 14, 44, 165, 725, 3607, 19624, 115127, 716177, 4675144, 31743253, 222710685, 1606581461, 11868655658, 89506275569, 687275710608, 5361744667232, 42423406909091, 339921273158836, 2754682455861719, 22553369622588850, 186375668479844528

STATUS

approved

editing