A173556 - OEIS

%I #2 Mar 30 2012 17:34:39

%S 1,2,4,4,0,0,6,4,0,4,2,4,0,4,4,4,0,0,0,0,0,0,0,0,0,0,0,0,2,4,0,4,4,0,

%T 0,4,6,4,0,4,4,0,0,4,4,4,0,0,0,0,0,0,0,0,0,6,4,0,4,4,0,0,4,4,0,4,4,0,

%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,4,0,4,4,0,0,4,4,0,4,0,0,4,6

%N Triangle T(n,m) = (prime(n)-1)*(prime(m)- 1) mod 8 read by rows.

%C Row sums are: 1, 6, 4, 14, 14, 4, 0, 18, 26, 4,...

%F t(n,m)=Mod[(Prime[n] - 1)*(Prime[m] - 1), 8]

%e The triangle (prime(n)-1)*(prime(m)-1) starts

%e 1;

%e 2,4 ;

%e 4,8,16 ;

%e 6,12,24,36 ;

%e 10,20,40,60,100 ;

%e 12,24,48,72,120,144 ;

%e 16,32,64,96,160,192,256 ;

%e and reduced mod 8, T(n,m) starts

%e 1;

%e 2, 4;

%e 4, 0, 0;

%e 6, 4, 0, 4;

%e 2, 4, 0, 4, 4;

%e 4, 0, 0, 0, 0, 0;

%e 0, 0, 0, 0, 0, 0, 0;

%e 2, 4, 0, 4, 4, 0, 0, 4;

%e 6, 4, 0, 4, 4, 0, 0, 4, 4;

%e 4, 0, 0, 0, 0, 0, 0, 0, 0, 0;

%t t[n_, m_] = Mod[(Prime[n] - 1)*(Prime[m] - 1), 8];

%t Table[Table[t[n, m], {m, 1, n}], {n, 1, 10}];

%t Flatten[%]

%K nonn,tabl,easy

%O 1,2

%A _Roger L. Bagula_, Feb 21 2010

%E Standardized nomenclature - the Assoc. Editors of the OEIS, Feb 24 2010