A155628 a(n) = 7^n-4^n+1^n.

1, 4, 34, 280, 2146, 15784, 113554, 807160, 5699266, 40091464, 281426674, 1973132440, 13824509986, 96821901544, 677954637394, 4746487768120, 33228635602306, 232613334118024, 1628344878433714, 11398620307466200

Offset: 0

Author

Mohammad K. Azarian, Jan 30 2009

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (12,-39,28).

Crossrefs

Cf. A155596, A155597, A155598, A155599, A155600, A155601, A155622, A155623, A155624, A155625, A155626, A155627.

Programs

Mathematica

Table[7^n-4^n+1,{n,0,20}] (* or *) LinearRecurrence[{12,-39,28},{1,4,34},20] (* Harvey P. Dale, Jul 16 2017 *)

PARI

a(n)=7^n-4^n+1 \\ Charles R Greathouse IV, Sep 24 2015

Formula

G.f.: 1/(1-7*x)-1/(1-4*x)+1/(1-x). E.g.f.: e^(7*x)-e^(4*x)+e^x.

a(n) = 11*a(n-1)-28*a(n-2)+18 with a(0)=1, a(1)=4. - Vincenzo Librandi, Jul 21 2010