A060352 a(n) = n*3^n - 1.

2, 17, 80, 323, 1214, 4373, 15308, 52487, 177146, 590489, 1948616, 6377291, 20726198, 66961565, 215233604, 688747535, 2195382770, 6973568801, 22082967872, 69735688019, 219667417262, 690383311397, 2165293113020, 6778308875543, 21182215236074, 66088511536553, 205891132094648

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..200

Paul Leyland, Factors of Cullen and Woodall numbers

Paul Leyland, Generalized Cullen and Woodall numbers

Amelia Carolina Sparavigna, The groupoids of Mersenne, Fermat, Cullen, Woodall and other Numbers and their representations by means of integer sequences, Politecnico di Torino, Italy (2019), [math.NT].

Amelia Carolina Sparavigna, Some Groupoids and their Representations by Means of Integer Sequences, International Journal of Sciences (2019) Vol. 8, No. 10.

Index entries for linear recurrences with constant coefficients, signature (7,-15,9).

Formula

G.f.: x*(2-3*x)*(1+3*x)/((1-x)*(1-3*x)^2). - Colin Barker, Apr 22 2012

a(n) = 7*a(n-1) - 15*a(n-2) + 9*a(n-3), a(1)=2, a(2)=17, a(3)=80. - Harvey P. Dale, Dec 14 2012

E.g.f.: 1 + exp(x)*(3*exp(2*x)*x - 1). - Stefano Spezia, Jan 05 2020

Mathematica

Table[n*3^n-1, {n, 50}] (* Vladimir Joseph Stephan Orlovsky, May 19 2011 *)
LinearRecurrence[{7, -15, 9}, {2, 17, 80}, 50] (* Harvey P. Dale, Dec 14 2012 *)

Prog

(PARI) a(n) = { n*3^n - 1 } \\ Harry J. Smith, Jul 04 2009

Crossrefs

Cf. A060353.

Sequence in context: A235471 A297411 A183175 * A215185 A002523 A360747

Adjacent sequences: A060349 A060350 A060351 * A060353 A060354 A060355

Keyword

nonn,easy,changed

Author

Jason Earls, Mar 31 2001

Status

approved