Question 1196601
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Hi

 {{{a[n]=a[1]+(n-1)*d}}}
 IF {{{a[1] = 4}}}, {{{a[2] = 8}}}, {{{a[3] = 12}}}, etc
{{{a[2]=4+(2-1)*d}}}
 {{{8=4+d}}}  and d = 4
{{{a[3]=4+(3-1)*4 = 12 }}}
and
{{{a[4]=4+(4-1)*4 = 16 }}}
and 
{{{a[5]=4+(5-1)*4 = 20 }}}
numbers in the perimeter row DO form an arithmetic sequence with d=4
Wish You the Best in your Studies.
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