A154681 - OEIS

%I #15 Sep 08 2022 08:45:40

%S 7,10,15,13,20,27,16,25,34,43,19,30,41,52,63,22,35,48,61,74,87,25,40,

%T 55,70,85,100,115,28,45,62,79,96,113,130,147,31,50,69,88,107,126,145,

%U 164,183,34,55,76,97,118,139,160,181,202,223,37,60,83,106,129,152

%N Triangle read by rows where T(m,n) = 2*m*n + m + n +3.

%C 2*T(m,n) - 5 = (2*n+1)*(2*m+1) is not prime.

%C First column: A112414; second column: A008587.

%H Vincenzo Librandi, <a href="/A154681/b154681.txt">Rows n = 1..100, flattened</a>

%e Triangle begins:

%e   7;

%e   10, 15;

%e   13, 20, 27;

%e   16, 25, 34, 43;

%e   19, 30, 41, 52,  63;

%e   22, 35, 48, 61,  74,  87;

%e   25, 40, 55, 70,  85, 100, 115;

%e   28, 45, 62, 79,  96, 113, 130, 147;

%e   31, 50, 69, 88, 107, 126, 145, 164, 183;

%e   34, 55, 76, 97, 118, 139, 160, 181, 202, 223; etc.

%t t[n_,k_]:=2 n*k + n + k + 3; Table[t[n, k], {n, 10}, {k, n}]//Flatten (* _vincenzo Librandi_, Nov 17 2012 *)

%o (Magma) [(2*n*k + n + k + 3): k in [1..n], n in [1..11]]; // _Vincenzo Librandi_, Nov 17 2012

%Y Cf. A153040, A008587, A089253, A112414.

%K nonn,tabl,easy

%O 1,1

%A _Vincenzo Librandi_, Jan 18 2009