A153236 - OEIS

%I #14 Sep 08 2022 08:45:39

%S 3,4,6,9,11,12,14,15,18,19,21,23,24,25,27,29,30,32,33,34,36,37,39,40,

%T 42,44,45,46,48,49,50,51,53,54,56,57,59,60,63,64,66,67,69,72,74,75,76,

%U 78,79,81,83,84,87,88,89,90,91,93,94,95,96,97

%N Numbers n such that 8*n + 3 is not prime.

%H Vincenzo Librandi, <a href="/A153236/b153236.txt">Table of n, a(n) for n = 1..1000</a>

%e Distribution of the terms in the following triangular array:

%e *;

%e *,*;

%e *,4,*;

%e 3,*,*,*;

%e *,*,*,12,*;

%e *,*,11,*,*,*;

%e *,9,*,*,*,24,*;

%e 6,*,*,*,23,*,*,*;

%e *,*,*,21,*,*,*,40,*;

%e *,*,18,*,*,*,39,*,*,*;

%e *,14,*,*,*,37,*,*,*,60,*;

%e 9,*,*,*,34,*,*,*,59,*,*,*; etc.

%e where * marks the non-integer values of (2*h*k + k + h - 1)/4 with h >= k >= 1. - _Vincenzo Librandi_, Jan 15 2013

%t Select[Range[0, 200], !PrimeQ[8 # + 3] &] (* _Vincenzo Librandi_, Jan 12 2013 *)

%o (Magma) [n: n in [0..110] | not IsPrime(8*n+3)]; // _Vincenzo Librandi_, Jan 12 2013

%Y Cf. A007520, A005124, A139487.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Dec 21 2008