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A173323 a(n) = 3*n! - 1. 6
2, 2, 5, 17, 71, 359, 2159, 15119, 120959, 1088639, 10886399, 119750399, 1437004799, 18681062399, 261534873599, 3923023103999, 62768369663999, 1067062284287999, 19207121117183999, 364935301226495999 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

FORMULA

a(0)=2, a(n) = n*a(n-1)+n-1. - Vincenzo Librandi, Sep 30 2013

D-finite with recurrence a(n) +(-n-2)*a(n-1) +(2*n-1)*a(n-2) +(-n+2)*a(n-3)=0. - R. J. Mathar, Mar 07 2022

MATHEMATICA

Table[3 n! - 1, {n, 0, 25}] (* Vincenzo Librandi, Sep 30 2013 *)

3*(Range[0, 20]!)-1 (* Harvey P. Dale, Oct 27 2015 *)

PROG

(MAGMA) [3*Factorial(n)-1: n in [0..25]]; /* or */ [2] cat [n eq 1 select n+1 else n*Self(n-1)+n-1: n in [1..25] ]; // Vincenzo Librandi, Sep 30 2013

CROSSREFS

Cf. sequences of the type k*n!-1: A033312 (k=1), A020543 (k=2), this sequence, A173321 (k=4), A173317 (k=5), A173316 (k=6).

Sequence in context: A259101 A184313 A158059 * A019099 A154647 A103890

Adjacent sequences:  A173320 A173321 A173322 * A173324 A173325 A173326

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Feb 16 2010

STATUS

approved

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Last modified August 15 15:31 EDT 2022. Contains 356148 sequences. (Running on oeis4.)