This site is supported by donations to The OEIS Foundation.

 Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A055730 Number of primes <= 5^n. 0
 0, 3, 9, 30, 114, 445, 1821, 7671, 33118, 145713, 650133, 2934858, 13375865, 61444585, 284140656, 1321453490, 6175961983, 28988040005, 136575061279, 645620925545, 3061129684411, 14552990145243, 69354801708586, 331251325552977, 1585299642009257, 7600886353341754, 36504944044424979, 175596829407110803, 845879609035799508, 4080206964520522386, 19705939422430380037, 95283357078617397618, 461221032128956299315 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA a(n) = A000720(A000351(n)). - Michel Marcus, Aug 25 2014 MATHEMATICA Table[PrimePi[5^n], {n, 0, 19}] PROG (PARI) a(n) = primepi(5^n); \\ Michel Marcus, Aug 25 2014 CROSSREFS Cf. A006880, A007053 and A040014. Sequence in context: A117428 A134168 A124427 * A120018 A091353 A279199 Adjacent sequences:  A055727 A055728 A055729 * A055731 A055732 A055733 KEYWORD nonn AUTHOR Robert G. Wilson v, Jun 09 2000 EXTENSIONS a(19) corrected by Henri Lifchitz, Nov 11 2012 a(20)-a(27) from Henri Lifchitz, Nov 11 2012 a(28)-a(32) from Henri Lifchitz, Aug 25 2014 Definition corrected by Jean-Claude Arbaut, Oct 07 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 11 22:04 EST 2018. Contains 318052 sequences. (Running on oeis4.)