login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A118672 Numbers divisible by prime(i)^i for some i. 2

%I #13 Apr 06 2021 02:57:55

%S 2,4,6,8,9,10,12,14,16,18,20,22,24,26,27,28,30,32,34,36,38,40,42,44,

%T 45,46,48,50,52,54,56,58,60,62,63,64,66,68,70,72,74,76,78,80,81,82,84,

%U 86,88,90,92,94,96,98,99,100,102,104,106,108,110,112,114,116,117,118,120

%N Numbers divisible by prime(i)^i for some i.

%C Any multiple of an element of this sequence is in the sequence. The primitive elements of this sequence are A062457.

%C The asymptotic density of this sequence is 1 - Product_{k>=1} (1 - 1/prime(k)^k) = 0.55929756713969708790... - _Amiram Eldar_, Apr 06 2021

%H Robert Israel, <a href="/A118672/b118672.txt">Table of n, a(n) for n = 1..10000</a>

%p N:= 1000: # to get all terms <= N

%p S:= {}:

%p for i from 1 do

%p v:= ithprime(i)^i;

%p if v > N then break fi;

%p S:= S union {seq(j,j=v..N,v)};

%p od:

%p sort(convert(S,list)); # _Robert Israel_, Mar 27 2018

%t seq[max_] := Module[{s = {}, p = 2, i = 1, q = 2}, While[q < max, s = Join[s, Range[q, max, q]]; p = NextPrime[p]; i++; q = p^i]; Union[s]]; seq[120] (* _Amiram Eldar_, Apr 06 2021 *)

%Y Cf. A062457, A000040.

%Y Complement of A325128.

%K nonn

%O 1,1

%A _Franklin T. Adams-Watters_, May 19 2006

%E An incorrect g.f. was deleted by _N. J. A. Sloane_, Sep 13 2009

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)