OFFSET
0,2
COMMENTS
Conjecture: a(n) = least positive whose base-4 up-variation is n; see column 1 of A297553.
LINKS
Clark Kimberling, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,16,-16)
FORMULA
a(n) = a(n-1) + 16*a(n-3) - 16*a(n-4), where a(0) = 1, a(1) = 4, a(2) = 7, a(3) = 19.
G.f.: (1 + 5 x + x^2 - 4 x^3)/(1 - x - 16 x^3 + 16 x^4).
MATHEMATICA
LinearRecurrence[{1, 0, 16, -16}, {1, 6, 7, 19}, 40]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jan 21 2018
STATUS
approved