OFFSET
1,1
COMMENTS
Numbers k such that the Motzkin number A001006(k) == 2 (mod 3).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Rob Burns, Asymptotic density of Motzkin numbers modulo small primes, arXiv:1611.04910 [math.NT], 2016.
MATHEMATICA
(* m = MotzkinNumber *) m[0] = 1; m[n_] := m[n] = m[n - 1] + Sum[ m[k]*m[n - 2 - k], {k, 0, n - 2}]; Select[ Range[1010], Mod[m[#], 3] == 2 &] (* Jean-François Alcover, Jul 10 2013 *)
Select[3*Range[350] - 1, DigitCount[# + 1, 3, 2] == 0 &] (* Amiram Eldar, Jun 04 2022 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Emeric Deutsch and Bruce E. Sagan, Dec 05 2003
EXTENSIONS
Offset corrected to 1 by Jean-François Alcover, Jun 23 2016
STATUS
approved