A334919 - OEIS

%I #52 Sep 08 2022 08:46:25

%S 5,8,9,13,16,17,18,21,23,25,28,29,30,33,37,38,40,41,43,44,45,48,49,51,

%T 53,56,57,58,61,62,63,65,68,69,72,73,77,78,79,81,82,83,84,85,86,88,89,

%U 93,95,96,97,98,100,101,103,105,106,107,108,109,113,114,117

%N Numbers of the form i + j + 3*i*j for i,j >= 1 together with numbers of the form -i - j + 3*i*j for i,j >= 2.

%e 5 is a term because 5 = 1+1+3*1*1.

%e 8 is a term because 8 = -2-2+3*2*2.

%e 16 is a term because 16 = 2+2+3*2*2.

%o (Magma) [m:m in [1..101]|exists(a){i:i in [1..m-1]|IsIntegral((m-i)/(1+3*i))} or exists(b){j:j in [2..m-1]|IsIntegral((m+j)/(-1+3*j)) and (m+j)/(-1+3*j) ge 2}]; // _Marius A. Burtea_, Jun 04 2020

%Y Complement of A335031.

%K nonn

%O 1,1

%A _Davide Rotondo_, May 16 2020