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!)
A004621 Divisible only by primes congruent to 3 mod 7. 1

%I #14 Oct 26 2023 00:43:09

%S 1,3,9,17,27,31,51,59,73,81,93,101,153,157,177,199,219,227,241,243,

%T 269,279,283,289,303,311,353,367,409,459,471,479,521,527,531,563,577,

%U 597,619,647,657,661,681,723,729,773,787,807,829,837,849,857,867,909,933

%N Divisible only by primes congruent to 3 mod 7.

%H Vincenzo Librandi, <a href="/A004621/b004621.txt">Table of n, a(n) for n = 1..1000</a>

%t ok[1]=True;ok[n_]:=And@@(Mod[#,7]==3&)/@FactorInteger[n][[All,1]];Select[Range[3000],ok] (* _Vincenzo Librandi_, Aug 20 2012 *)

%o (Magma) [n: n in [1..1000] | forall{d: d in PrimeDivisors(n) | d mod 7 eq 3}]; // _Vincenzo Librandi_, Aug 20 2012

%Y Cf. A045437 (divisors).

%K nonn

%O 1,2

%A _N. J. A. Sloane_

%E Offset changed from 0 to 1 by _Vincenzo Librandi_, Aug 20 2012

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 March 29 08:46 EDT 2024. Contains 371267 sequences. (Running on oeis4.)