The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A036318 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A036318

Composite numbers whose prime factors contain no digits other than 4 and 7.
(history; published version)

#25 by Michel Marcus at Sun May 22 05:51:08 EDT 2022

STATUS

reviewed

approved

#24 by Joerg Arndt at Sun May 22 05:46:05 EDT 2022

STATUS

proposed

reviewed

#23 by Amiram Eldar at Sun May 22 05:28:15 EDT 2022

STATUS

editing

proposed

#22 by Amiram Eldar at Sun May 22 05:10:21 EDT 2022

LINKS

<a href="/index/Pri#prime_factors">Index entries sequences related to prime factors</a>.

FORMULA

Sum_{n>=1} 1/a(n) = Product_{p in A020465} (p/(p - 1)) - Sum_{p in A020465} 1/p - 1 = 0.0279830135... . - Amiram Eldar, May 22 2022

STATUS

approved

editing

#21 by Andrew Howroyd at Sat Jun 19 22:41:57 EDT 2021

STATUS

proposed

approved

#20 by Jon E. Schoenfield at Sat Jun 19 22:30:16 EDT 2021

STATUS

editing

proposed

#19 by Jon E. Schoenfield at Sat Jun 19 22:30:15 EDT 2021

NAME

Composite numbers n such that digits of whose prime factors of n are either contain no digits other than 4 or and 7.

STATUS

approved

editing

#18 by N. J. A. Sloane at Sun Oct 18 15:51:03 EDT 2020

STATUS

proposed

approved

#17 by David A. Corneth at Sat Oct 17 19:10:25 EDT 2020

STATUS

editing

proposed

#16 by David A. Corneth at Sat Oct 17 19:04:11 EDT 2020

KEYWORD

nonn,easy,base,changed