The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A128950 a(n) is equal to the number of positive integers m less than or equal to 10^n such that m is not divisible by the prime 7 and is not divisible by at least one of the primes 2, 3 and 5. 1
 83, 829, 8286, 82858, 828571, 8285715, 82857143, 828571429, 8285714286, 82857142858, 828571428571, 8285714285715, 82857142857143, 828571428571429, 8285714285714286, 82857142857142858, 828571428571428571 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 2..1000 Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets FORMULA a(n) = 10^n - floor(10^n/7) - floor(10^n/30) + floor(10^n/210). EXAMPLE a(6) = 10^6 - floor(10^6/7) - floor(10^6/30) + floor(10^6/210) = 1000000 - floor(142857.142...) - floor(33333.333...) + floor(4761.904...) = 1000000 - 142857 - 33333 + 4761 = 828571. MAPLE f := n->10^n-floor(10^n/7)-floor(10^n/30)+floor(10^n/210); PROG (MAGMA) [10^n-Floor(10^n/7)-Floor(10^n/30)+Floor(10^n/210): n in [2..20]]; // Vincenzo Librandi, Oct 02 2011 CROSSREFS Sequence in context: A069596 A290407 A112766 * A068851 A250083 A292284 Adjacent sequences:  A128947 A128948 A128949 * A128951 A128952 A128953 KEYWORD nonn AUTHOR Milan Janjic, Apr 28 2007 EXTENSIONS Example edited by Jon E. Schoenfield, Nov 17 2018 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 January 17 23:37 EST 2020. Contains 330995 sequences. (Running on oeis4.)