OFFSET
0,1
COMMENTS
Numbers whose digital root is 4. - L. Edson Jeffery, Nov 26 2016
REFERENCES
R. K. Guy, Unsolved Problems in Number Theory, Springer, 1st edition, 1981. See section D5.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..5000
Tanya Khovanova, Recursive Sequences
Index entries for linear recurrences with constant coefficients, signature (2,-1).
FORMULA
G.f.: (4 + 5*x)/(x - 1)^2. - R. J. Mathar, Jul 14 2016
A010888(a(n)) = 4. - L. Edson Jeffery, Nov 26 2016
E.g.f.: exp(x)*(4 + 9*x). - Stefano Spezia, Dec 25 2022
MATHEMATICA
Range[4, 1000, 9] (* Vladimir Joseph Stephan Orlovsky, May 28 2011 *)
PROG
(PARI) forstep(n=4, 500, 9, print1(n", ")) \\ Charles R Greathouse IV, May 28 2011
(Magma) [9*n+4: n in [0..60]]; // Vincenzo Librandi, Jul 23 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved