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A172090 Let f(0) = 1, f(1) = -2, f(n) = n*f(n-1) - 2 if |f(n-1)| is prime and f(n) = n*f(n-1)/(n+1) otherwise.  Then t(n,m) = f(n-m) + f(m) - f(n). 0

%I

%S 1,1,1,1,2,1,1,1,1,1,1,1,0,1,1,1,1,0,0,1,1,1,1,0,0,0,1,1,1,1,0,0,0,0,

%T 1,1,1,1,0,0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1,1,1,0,0,0,0,0,0,0,1,1

%N Let f(0) = 1, f(1) = -2, f(n) = n*f(n-1) - 2 if |f(n-1)| is prime and f(n) = n*f(n-1)/(n+1) otherwise. Then t(n,m) = f(n-m) + f(m) - f(n).

%C Row sums are 1, 2, 4, 4, 4, 4, 4, 4, 4, 4, 4, ...; f(n) is 1, -2, -6, -9, -12, -15, -18, -21, -24, -27, -30, -33, -36, -39, -42, -45, -48, -51, -54, -57, -60, -63, -66, -69, -72, -75, -78, -81, -84, -87, -90, ....

%e {1},

%e {1, 1},

%e {1, 2, 1},

%e {1, 1, 1, 1},

%e {1, 1, 0, 1, 1},

%e {1, 1, 0, 0, 1, 1},

%e {1, 1, 0, 0, 0, 1, 1},

%e {1, 1, 0, 0, 0, 0, 1, 1},

%e {1, 1, 0, 0, 0, 0, 0, 1, 1},

%e {1, 1, 0, 0, 0, 0, 0, 0, 1, 1},

%e {1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1}

%t f[0]=1;f[1]=-2;

%t f[n_]:=f[n]=If[PrimeQ[Abs[f[n-1]]],f[n-1]*n-2,f[n-1]*n/(n-1)];

%t Flatten[Table[Table[ -f[n]+f[n-k]+f[k],{k,0,n}],{n,0,10}]]

%K nonn,tabl,uned

%O 0,5

%A _Roger L. Bagula_, Jan 25 2010

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Last modified July 16 08:37 EDT 2020. Contains 335781 sequences. (Running on oeis4.)