A177019 a(n) = 3*10^(2*n) + 3*10^n + 1.

7, 331, 30301, 3003001, 300030001, 30000300001, 3000003000001, 300000030000001, 30000000300000001, 3000000003000000001, 300000000030000000001, 30000000000300000000001, 3000000000003000000000001, 300000000000030000000000001, 30000000000000300000000000001, 3000000000000003000000000000001

Offset: 0

Author

Vincenzo Librandi, May 24 2010

Keywords

• nonn
• easy

Examples

			For n=0, a(0)=7; n=1, a(1)=3*10^2+3*10+1=331.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..100
• Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000).

Crossrefs

Cf. A011557, A098608.

Programs

Magma

[(3*10^(2*n)+3*10^n+1): n in [0..15]];

Mathematica

CoefficientList[Series[(7 - 446 x + 1330 x^2)/((1 - x)(1 - 10 x) (1 - 100 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Aug 19 2014 *)

Formula

G.f.: (7-446*x+1330*x^2)/((1-x)*(1-10*x)*(1-100*x)). - Vincenzo Librandi, Aug 19 2014

E.g.f.: exp(x)*(1 + 3*exp(9*x) + 3*exp(99*x)). - Stefano Spezia, Aug 05 2024