a(n) = 1^n + 2^n + 3^n.

Terms

a(0) =3a(1) =6a(2) =14a(3) =36a(4) =98a(5) =276a(6) =794a(7) =2316a(8) =6818a(9) =20196a(10) =60074a(11) =179196a(12) =535538a(13) =1602516a(14) =4799354a(15) =14381676a(16) =43112258a(17) =129271236a(18) =387682634a(19) =1162785756a(20) =3487832978a(21) =10462450356a(22) =31385253914a(23) =94151567436a(24) =282446313698a(25) =847322163876