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A155551 Triangle read by rows where T(m,n)=2*m*n + m + n - 9.

%I A155551 #14 Sep 08 2022 08:45:40
%S A155551 -5,-2,3,1,8,15,4,13,22,31,7,18,29,40,51,10,23,36,49,62,75,13,28,43,
%T A155551 58,73,88,103,16,33,50,67,84,101,118,135,19,38,57,76,95,114,133,152,
%U A155551 171,22,43,64,85,106,127,148,169,190,211,25,48,71,94,117,140,163,186,209
%N A155551 Triangle read by rows where T(m,n)=2*m*n + m + n - 9.
%C A155551 The numbers 2*T(m,n)+19 =(2*n+1)*(2*m+1) are not prime.
%C A155551 First column: A016777, second column: A016885, third column: A016993, fourth column: A017209. - _Vincenzo Librandi_, Nov 20 2012
%H A155551 Vincenzo Librandi, <a href="/A155551/b155551.txt">Rows n = 1..100, flattened</a>
%e A155551 Triangle begins:
%e A155551 -5;
%e A155551 -2, 3;
%e A155551 1,  8,  15;
%e A155551 4,  13, 22, 31;
%e A155551 7,  18, 29, 40, 51;
%e A155551 10, 23, 36, 49, 62,  75;
%e A155551 13, 28, 43, 58, 73,  88,  103;
%e A155551 16, 33, 50, 67, 84,  101, 118, 135;
%e A155551 19, 38, 57, 76, 95,  114, 133, 152, 171;
%e A155551 22, 43, 64, 85, 106, 127, 148, 169, 190, 211; etc.
%t A155551 t[n_,k_]:=2 n*k + n + k - 9; Table[t[n, k], {n, 15}, {k, n}]//Flatten (* _Vincenzo Librandi_, Nov 20 2012 *)
%o A155551 (Magma) [2*n*k + n + k - 9: k in [1..n], n in [1..11]]; // _Vincenzo Librandi_, Nov 20 2012
%Y A155551 Cf. A153143, A153144, A016777, A016885, A016993, A017209.
%K A155551 tabl,sign,easy
%O A155551 1,1
%A A155551 _Vincenzo Librandi_, Jan 24 2009