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A061434
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a(n) is the smallest n-digit cube.
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4
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1, 27, 125, 1000, 10648, 103823, 1000000, 10077696, 100544625, 1000000000, 10007873875, 100026577288, 1000000000000, 10000909453625, 100000721719296, 1000000000000000, 10000073940248384, 100000075387171679, 1000000000000000000, 10000004316234262875
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internal format)
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = ceiling(10^((n-1)/3))^3. - Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003
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EXAMPLE
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a(4) = 1000 = 10^3 has 4 digits while 9^3 = 729 has 3 digits.
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MAPLE
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A061434 := n->ceil(10^((n-1)/3))^3;
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MATHEMATICA
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Table[Ceiling[Surd[10^n, 3]]^3, {n, 0, 20}] (* Harvey P. Dale, Oct 09 2023 *)
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PROG
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(Python)
from sympy import integer_nthroot
def a(n):
r, exact = integer_nthroot(10**(n-1), 3)
return 10**(n-1) if exact else (r+1)**3
(PARI) a(n) = ceil(10^((n-1)/3))^3; \\ Michel Marcus, Jan 27 2021
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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EXTENSIONS
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More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003
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STATUS
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approved
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