OFFSET
1,1
COMMENTS
Consider natural numbers A000027 as a triangle 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc., then the a(n) indicate rows without a square.
Similar to Beatty sequences: where a pair of complementary Beatty sequences are floor(n*c) and floor(n*c/(c-1)) for c an irrational constant > 1, these pairs of complementary sequences are in general round(n*c) and round((n-1/2)*c/(c-1)) for c an irrational constant > 1.
This sequence is an inhomogeneous Beatty sequence s(alpha,rho) with slope alpha = 2 + sqrt(2), and intercept rho = -1/2 - sqrt(2)/2. - Michel Dekking, Sep 15 2022
Let D := 3,4,3,3,4,3,4,3,3,4,3,4,3,4,3,3,4,3,... be the sequence of first differences of (a(n)). It follows from Yasutomi's criterion that D is NOT the fixed point of a morphism. - Michel Dekking, Sep 20 2022
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
A. S. Fraenkel, The bracket function and complementary sets of integers, Canadian J. of Math. 21 (1969) 6-27. (Theorem XI)
Clark Kimberling, Beatty sequences and trigonometric functions, Integers 16 (2016), #A15.
S.-I. Yasutomi, On Sturmian sequences which are invariant under some substitutions, on ResearchGate.
FORMULA
a(n) = round((n - 1/2)*(2 + sqrt(2))) = round(n*3.4142...-1.7071...).
EXAMPLE
round(m*sqrt(2)) starts 1,3,4,6,7,8,10,11,13,... so this sequence must start 2,5,9,12,...
PROG
(PARI) { f=2 + sqrt(2); t=f/2; for (n=1, 1000, write("b063957.txt", n, " ", round(n*f - t)) ) } \\ Harry J. Smith, Sep 03 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Henry Bottomley, Sep 04 2001
STATUS
approved