A321972 Numbers k for which A048198(k)=3.

1, 2, 4, 7, 10, 11, 23, 28, 31, 35, 46, 86, 88, 109, 128, 130, 143, 145, 149, 161, 187, 200, 214, 224, 227, 238, 266, 269, 271, 280, 346, 353, 385, 392, 413, 452, 464, 479, 497, 523, 544, 548, 565, 574, 620, 655, 683, 721, 788, 809, 829, 854, 901, 928, 934, 1027, 1043, 1046, 1178, 1183, 1204

Offset: 1

Author

Robert Israel, Nov 22 2018

Keywords

• nonn

Comments

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

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

No terms are divisible by 3.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A048198.

Programs

Maple

filter:= n -> nops(select(isprime,[10*n-3,10*n-1,10*n+1,10*n+3]))=3:
select(filter, [$1..1000]); # Robert Israel, Nov 22 2018

Mathematica

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