A342446 Square table read by antidiagonals downwards: T(n,k) = floor((4/(4^(1/2^n)-1))^(1/2^k)).

1, 4, 1, 9, 2, 1, 21, 3, 1, 1, 44, 4, 1, 1, 1, 90, 6, 2, 1, 1, 1, 182, 9, 2, 1, 1, 1, 1, 367, 13, 3, 1, 1, 1, 1, 1, 736, 19, 3, 1, 1, 1, 1, 1, 1, 1475, 27, 4, 1, 1, 1, 1, 1, 1, 1, 2952, 38, 5, 2, 1, 1, 1, 1, 1, 1, 1, 5907, 54, 6, 2, 1, 1, 1, 1, 1, 1, 1, 1

Offset

0,2

Comments

Every positive integer occurs infinitely often.

Links

Table of n, a(n) for n=0..77.

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

Sequence in context: A331151 A085383 A365539 * A306744 A304526 A333352

Adjacent sequences: A342443 A342444 A342445 * A342447 A342448 A342449

Keyword

nonn,tabl

Author

Franz Vrabec, Mar 12 2021

Status

approved