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A144670 Triangle read by rows where T(m,n)=2mn+m+n-7.

%I A144670 #10 Jun 02 2025 00:35:34
%S A144670 -3,0,5,3,10,17,6,15,24,33,9,20,31,42,53,12,25,38,51,64,77,15,30,45,
%T A144670 60,75,90,105,18,35,52,69,86,103,120,137,21,40,59,78,97,116,135,154,
%U A144670 173,24,45,66,87,108,129,150,171,192,213,27,50,73,96,119,142,165,188,211,234,257
%N A144670 Triangle read by rows where T(m,n)=2mn+m+n-7.
%C A144670 Numbers n such that, if 2^(s-1)=n then [A144487] is not prime.
%C A144670 Let p (prime number), n=(p^2-15)/2 mod(p).
%H A144670 Vincenzo Librandi, <a href="/A144670/b144670.txt">Rows n = 100, flattened</a>
%e A144670 Triangle begins:
%e A144670 -3;
%e A144670 0, 5;
%e A144670 3, 10, 17;
%e A144670 6, 15, 24, 33;
%e A144670 9, 20, 31, 42, 53;
%e A144670 12, 25, 38, 51, 64, 77;
%e A144670 15, 30, 45, 60, 75, 90, 105;
%e A144670 18, 35, 52, 69, 86, 103, 120, 137;
%e A144670 21, 40, 59, 78, 97, 116, 135, 154, 173;
%e A144670 24, 45, 66, 87, 108, 129, 150, 171, 192, 213;
%e A144670 = = = = = = = =
%t A144670 t[n_,k_]:=2 n*k+n+k-7; Table[t[n, k], {n, 12}, {k, n}] // Flatten (* _Vincenzo Librandi_, Oct 15 2012 *)
%o A144670 (Magma) [2*n*k + n + k -7: k in [1..n], n in [1..12]]; // _Vincenzo Librandi_, Oct 15 2012
%Y A144670 Cf. A057197, A144487.
%K A144670 tabl,sign
%O A144670 1,1
%A A144670 _Vincenzo Librandi_, Jan 28 2009