Question 1161716
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{{{a[1] = 4 }}}
{{{a[2] = -3}}}    difference is -7 (-3-4 = -7), we can write:  -3 = 4+1(-7)
{{{a[3] = -10}}}   difference is -7 (-10-(-3) = -7), write:    -10 = 4+2(-7)

{{{a[n] = 4 + (n-1)(-7) }}}

or more commonly written: {{{ highlight(a[n] = 4 - 7*(n-1)) }}}, n=1,2,3,...