Question Number 82365 by M±th+et£s last updated on 20/Feb/20
Commented by mr W last updated on 21/Feb/20
$${a}_{{n}} =\mathrm{1}+\frac{\mathrm{3}\left({n}−\mathrm{1}\right){n}}{\mathrm{2}} \\ $$
Commented by mr W last updated on 22/Feb/20
$${am}\:{i}\:{right}? \\ $$
Commented by M±th+et£s last updated on 22/Feb/20
$${yes}\:{sir} \\ $$