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Triangle read by rows where T(m,n)=2*m*n + m + n - 6.
4

%I #10 Sep 08 2022 08:45:40

%S -2,1,6,4,11,18,7,16,25,34,10,21,32,43,54,13,26,39,52,65,78,16,31,46,

%T 61,76,91,106,19,36,53,70,87,104,121,138,22,41,60,79,98,117,136,155,

%U 174,25,46,67,88,109,130,151,172,193,214,28,51,74,97,120,143,166,189,212

%N Triangle read by rows where T(m,n)=2*m*n + m + n - 6.

%C Numbers n such that 2n+13 is not prime.

%C First column: A016777, second column: A016861, third column: A017029, fourth column: A017245. - _Vincenzo Librandi_, Nov 21 2012

%H Vincenzo Librandi, <a href="/A155550/b155550.txt">Rows n = 1..100, flattened</a>

%e Triangle begins:

%e -2;

%e 1, 6;

%e 4, 11, 18;

%e 7, 16, 25, 34;

%e 10, 21, 32, 43, 54;

%e 13, 26, 39, 52, 65, 78;

%e 16, 31, 46, 61, 76, 91, 106;

%e 19, 36, 53, 70, 87, 104, 121, 138;

%e 22, 41, 60, 79, 98, 117, 136, 155, 174;

%e 25, 46, 67, 88, 109, 130, 151, 172, 193, 214; etc.

%t t[n_,k_]:= 2 n*k + n + k - 6; Table[t[n, k], {n, 15}, {k, n}]//Flatten (* _Vincenzo Librandi_, Nov 21 2012 *)

%o (Magma) [2*n*k + n + k - 6: k in [1..n], n in [1..11]]; // _Vincenzo Librandi_, Nov 21 2012

%Y Cf. A153082, A016777, A016861, A017029, A017245.

%K tabl,sign

%O 1,1

%A _Vincenzo Librandi_, Jan 24 2009