A321972 - OEIS

%I #13 Nov 29 2018 03:01:19

%S 1,2,4,7,10,11,23,28,31,35,46,86,88,109,128,130,143,145,149,161,187,

%T 200,214,224,227,238,266,269,271,280,346,353,385,392,413,452,464,479,

%U 497,523,544,548,565,574,620,655,683,721,788,809,829,854,901,928,934,1027,1043,1046,1178,1183,1204

%N Numbers k for which A048198(k)=3.

%C Numbers k for which three of 10*k-3, 10*k-1, 10*k+1, 10*k+3 are prime.

%C Note: they can't all be prime because at least one must be divisible by 3.

%C No terms are divisible by 3.

%H Robert Israel, <a href="/A321972/b321972.txt">Table of n, a(n) for n = 1..10000</a>

%p filter:= n -> nops(select(isprime,[10*n-3,10*n-1,10*n+1,10*n+3]))=3:

%p select(filter, [$1..1000]); # _Robert Israel_, Nov 22 2018

%t Select[Range[1204], AllTrue[Rest@Sort@PrimeQ[10 # + {-3, -1, 1, 3}], TrueQ] &] (* _Amiram Eldar_, Nov 22 2018 *)

%Y Cf. A048198.

%K nonn

%O 1,2

%A _Robert Israel_, Nov 22 2018