Using mathematical Induction, the numbers an ′s are defined by a0=1, an+1=3n2+n+an(n≥0) Then an=
n3+n2+1
n3−n2+1
n3−n2
n3+n2
Putting n = 0, 1, 2, ………………. n – 1 and adding an−a0=3∑(n−1)2+∑n⇒an=n3−n2+1