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A155546 Triangle read by rows where T(m,n)=2mn + m + n - 5, 1<=n<=m.

%I A155546 #10 Sep 08 2022 08:45:40
%S A155546 -1,2,7,5,12,19,8,17,26,35,11,22,33,44,55,14,27,40,53,66,79,17,32,47,
%T A155546 62,77,92,107,20,37,54,71,88,105,122,139,23,42,61,80,99,118,137,156,
%U A155546 175,26,47,68,89,110,131,152,173,194,215,29,52,75,98,121,144,167,190,213
%N A155546 Triangle read by rows where T(m,n)=2mn + m + n - 5, 1<=n<=m.
%C A155546 2*T(m,n)+11 = (2*m+1)*(2*n+1) is not prime.
%C A155546 First column: A016789, second column: A016873, third column: A017041, fourth column: A017257. - _Vincenzo Librandi_, Nov 21 2012
%H A155546 Vincenzo Librandi, <a href="/A155546/b155546.txt">Rows n = 1..100, flattened</a>
%e A155546 Triangle begins:
%e A155546 -1;
%e A155546 2,  7;
%e A155546 5,  12, 19;
%e A155546 8,  17, 26, 35;
%e A155546 11, 22, 33, 44, 55;
%e A155546 14, 27, 40, 53, 66,  79;
%e A155546 17, 32, 47, 62, 77,  92,  107;
%e A155546 20, 37, 54, 71, 88,  105, 122, 139;
%e A155546 23, 42, 61, 80, 99,  118, 137, 156, 175;
%e A155546 26, 47, 68, 89, 110, 131, 152, 173, 194, 215; etc.
%t A155546 t[n_,k_]:= 2 n*k + n + k - 5; Table[t[n, k], {n, 15}, {k, n}]//Flatten (* _Vincenzo Librandi_, Nov 21 2012 *)
%o A155546 (Magma) [2*n*k + n + k - 5: k in [1..n], n in [1..11]]; // _Vincenzo Librandi_, Nov 21 2012
%Y A155546 Cf. A101448, A153083, A016789, A016873, A017041, A017257.
%K A155546 tabl,sign,easy
%O A155546 1,2
%A A155546 _Vincenzo Librandi_, Jan 24 2009