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

 

Logo

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!)
A145586 a(n) = number of numbers removed in each step of Eratosthenes' sieve for 2^8. 0

%I

%S 127,42,16,8,5,3

%N a(n) = number of numbers removed in each step of Eratosthenes' sieve for 2^8.

%C Number of steps in Eratosthenes' sieve for 2^n is A060967(n).

%C Number of primes less than 2^8 is equal = 2^8 - (sum all of numbers in this sequence) - 1 = A007053(8).

%t f3[k_Integer?Positive, i_Integer?Positive] := Module[{f, m, r, p}, p = Transpose[{r = Range[2, i], Prime[r]}];f[x_] := Catch[Fold[If[Mod[x, #2[[2]]] == 0, Throw[m[ #2[[1]]] = m[ #2[[1]]] + 1], #1] &, If[Mod[x, 2] == 0, Throw[m[1] = m[1] + 1]], p]]; Table[m[n] = -1, {n, i}]; f /@ Range[k]; Table[m[n], {n, i}]];nn = 8; kk = PrimePi[Sqrt[2^nn]]; t3 = f3[2^nn, kk] (* Bob Hanlon (hanlonr(AT)cox.net), Oct 14 2008 *)

%Y Cf. A006880, A122121, A145532-A145540, A145583-A145592.

%K fini,nonn

%O 1,1

%A _Artur Jasinski_ with assistance from Bob Hanlon (hanlonr(AT)cox.net), Oct 14 2008

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 20 05:30 EST 2020. Contains 331067 sequences. (Running on oeis4.)