OFFSET
0,2
COMMENTS
For n > 3, also the number of (not necessarily maximal) cliques in the n-web graph. - Eric W. Weisstein, Nov 29 2017
The number of notes in a musical scale of n octaves. - Geoffrey Trueman Falk, Feb 16 2023
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..5000
Tanya Khovanova, Recursive Sequences
Eric Weisstein's World of Mathematics, Clique
Eric Weisstein's World of Mathematics, Web Graph
Index entries for linear recurrences with constant coefficients, signature (2,-1).
FORMULA
a(n) = 7*n + 1.
G.f.: (1+6*x)/(1-x)^2.
From Elmo R. Oliveira, Mar 07 2024: (Start)
a(n) = 2*a(n-1) - a(n-2).
E.g.f.: (1 + 7*x)*exp(x). (End)
MAPLE
MATHEMATICA
7*Range[0, 55] + 1 (* Alonso del Arte, Oct 26 2014 *)
Table[7 n + 1, {n, 0, 20}] (* Eric W. Weisstein, Nov 29 2017 *)
LinearRecurrence[{2, -1}, {8, 15}, {0, 20}] (* Eric W. Weisstein, Nov 29 2017 *)
CoefficientList[Series[(1 + 6 x)/(-1 + x)^2, {x, 0, 20}], x] (* Eric W. Weisstein, Nov 29 2017 *)
PROG
(Magma) [7*n+1: n in [0..60]]; // Vincenzo Librandi, May 28 2011
(Haskell)
a016993 = (+ 1) . (* 7)
a016993_list = [1, 8 ..] -- Reinhard Zumkeller, Jan 25 2013
(PARI) a(n)=7*n+1 \\ Charles R Greathouse IV, Jul 10 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved