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A294664
Numbers n such that the largest digit of n^3 is 4.
6
7, 68, 70, 324, 680, 700, 3240, 6800, 7000, 7618, 31177, 32400, 52308, 68000, 69314, 70000, 76180, 311770, 324000, 353068, 523080, 680000, 693140, 700000, 756658, 761800, 1039247, 2715974, 2732441, 3117700, 3240000, 3511617, 3530680, 4689368, 5230800, 6800000, 6931400, 7000000
OFFSET
1,1
COMMENTS
For any term a(n), all numbers of the form a(n)*10^k, k >= 0, are in this sequence. Primitive terms, i.e., not of this form (or equivalently: without trailing '0'), are 7, 68, 324, 7618, 31177, 52308, 69314, 353068, 756658, 1039247, 2715974, 2732441, 3511617, 4689368, 7571814, 12811968, 15904541, ...
All terms have last nonzero digit 1, 4, 7 or 8 and leading digit <= 7. - Robert Israel, Nov 13 2017
The number formed by the first m digits of a term is always less than c*10^m with c = (4/9)^(1/3) = .7631428283688879... - M. F. Hasler, Nov 13 2017
EXAMPLE
7 is in the sequence because the largest digit of 7^3 = 343 is 4.
MAPLE
select(n -> max(convert(n^3, base, 10))=4, [$1..10^6]); # Robert Israel, Nov 13 2017
PROG
(PARI) for(n=1, 2e8, vecmax(digits(n^3))==4&&print1(n", "))
CROSSREFS
Cf. A294663 (the corresponding cubes), A278937, A294665, A294996 - A294999 (analog for digits 3, 5, 6 - 9); A277961 (analog for squares).
Cf. A000578 (the cubes).
Sequence in context: A082698 A182127 A093170 * A120079 A297502 A087567
KEYWORD
nonn,base
AUTHOR
M. F. Hasler, Nov 12 2017
STATUS
approved