Question 1029294
{{{d=2m-(m-1)}}}
{{{d=2m-m+1}}}
{{{d=m+1}}}
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{{{a[n]=m-1+(n-1)(m+1)}}}
{{{a[1]=m-1}}}
{{{a[2]=m-1+m+1=2m}}}
{{{a[3]=m-1+2m+2=3m+1}}}
{{{a[4]=m-1+3m+3=4m+2}}}
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{{{a[20]=m-1+(20-1)(m+1)}}}
{{{a[20]=m-1+19m+19}}}
{{{a[20]=20m+18}}}
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Without knowing another piece of information, you cannot get numerical values.