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A061434 a(n) is the smallest n-digit cube. 4
1, 27, 125, 1000, 10648, 103823, 1000000, 10077696, 100544625, 1000000000, 10007873875, 100026577288, 1000000000000, 10000909453625, 100000721719296, 1000000000000000, 10000073940248384, 100000075387171679, 1000000000000000000, 10000004316234262875 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..20.

FORMULA

a(n) = ceiling(10^((n-1)/3))^3. - Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

EXAMPLE

a(4) = 1000 = 10^3 has 4 digits while 9^3 = 729 has 3 digits.

MAPLE

A061434 := n->ceil(10^((n-1)/3))^3;

PROG

(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

print([a(n) for n in range(1, 21)]) # Michael S. Branicky, Jan 27 2021

(PARI) a(n) = ceil(10^((n-1)/3))^3; \\ Michel Marcus, Jan 27 2021

CROSSREFS

Cf. A000578, A061432, A061433.

Sequence in context: A016755 A074100 A082610 * A092770 A253103 A321486

Adjacent sequences:  A061431 A061432 A061433 * A061435 A061436 A061437

KEYWORD

nonn,base,easy

AUTHOR

Amarnath Murthy, May 03 2001

EXTENSIONS

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

STATUS

approved

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Last modified September 24 21:05 EDT 2021. Contains 347651 sequences. (Running on oeis4.)