a(n) = Sum_{j=0..14} n^j.A104682a(n) = Sum_{j=0..14} n^j.Terms a(0) =1a(1) =15a(2) =32767a(3) =7174453a(4) =357913941a(5) =7629394531a(6) =94036996915a(7) =791260251657External referencesoeis: A104682