|
%I #9 Jul 26 2017 15:49:22
%S 42,105,231,399,483,861,987,1113,1281,1491,1869,2121,2247,2667,2751,
%T 3129,3423,5649,5691,5817,7539,8169,8421,8589,9807,10563,10689,10983,
%U 11361,13881,14511,14889,15519,17031,17409,18627,19761,20391,21189
%N Interprimes (A024675) which are of the form s*prime, s=21.
%C Interprimes of the form s*prime are in A075277-A075296 ( s = 2 - 21 ). Case s=1 is impossible.
%H David A. Corneth, <a href="/A075296/b075296.txt">Table of n, a(n) for n = 1..10000</a>
%e 231 is an interprime and 231/21 = 11 is prime.
%t s=21; Select[Table[(Prime[n+1]+Prime[n])/2, {n, 2, 14000}], PrimeQ[ #/s]&]
%o (PARI) first(n, {m=21}) = {my(res = List(), p); forprime(p=2, oo, if(precprime(m*p) + nextprime(m*p) == 2*m*p, listput(res, m*p); if(#res>=n,return(res))))} \\ _David A. Corneth_, Jul 26 2017
%Y Cf. A024675, A075277-A075296.
%K easy,nonn
%O 1,1
%A _Zak Seidov_, Sep 12 2002
|
