Question 1086935
{{{a[1]=4}}}
{{{a[n]=a[n-1]+3}}} for {{{n>=2}}}

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{{{a[1]=4}}}
{{{d=3}}}
{{{a[n]=a[1]+(n-1)*d}}}
{{{a[n]=4+(n-1)3}}}
{{{a[n]=4+3n-3}}}
{{{a[n]=3n+1}}}