OFFSET
0,2
COMMENTS
Every positive integer occurs infinitely often.
LINKS
N. J. Fine and Marcin E. Kuczma, Writing Integers with Exactly Three Fours, Problem E 3363 [1990, 63], Amer. Math. Monthly, Vol. 99 (1992), No. 2, pp. 163-164.
FORMULA
T(n,k) = floor((4/(4^(1/2^n)-1))^(1/2^k)).
EXAMPLE
T(2,1) = floor((4/(4^(1/4)-1))^(1/2)) = floor(sqrt(4/(sqrt(2)-1))) = floor(3.1075...) = 3.
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Franz Vrabec, Mar 12 2021
STATUS
approved