OFFSET
0,1
COMMENTS
Numbers whose digital root is 7. - Halfdan Skjerning, Mar 15 2018
LINKS
Tanya Khovanova, Recursive Sequences
J. Laroche & N. J. A. Sloane, Correspondence, 1977
Leo Tavares, Illustration: Triple Triangular Frames
Index entries for linear recurrences with constant coefficients, signature (2,-1).
FORMULA
a(n) = 18*n - a(n-1) + 5, with a(0)=7. - Vincenzo Librandi, Dec 24 2010
G.f.: (7+2*x)/(1-x)^2. - Vincenzo Librandi, Apr 30 2015
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>2. - Vincenzo Librandi, Apr 30 2015
MATHEMATICA
Range[7, 1000, 9] (* Vladimir Joseph Stephan Orlovsky, May 28 2011 *)
Table[9 n + 7, {n, 0, 70}] (* or *) CoefficientList[Series[(7 + 2 x)/(1 - x)^2, {x, 0, 60}], x] (* Vincenzo Librandi, Apr 30 2015 *)
LinearRecurrence[{2, -1}, {7, 16}, 60] (* Harvey P. Dale, Jul 30 2024 *)
PROG
(Magma) [9*n+7: n in [0..60]]; // Vincenzo Librandi, Apr 30 2015
(PARI) vector(100, n, 9*n-2) \\ Derek Orr, Apr 30 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved