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A364528
Number of 1's required to build -n using +, -, *, and parentheses.
0
3, 4, 5, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 11, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 13, 12, 12, 12, 12, 12, 13, 13, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 14, 13, 13, 13, 14, 13, 14, 13, 13
OFFSET
1,1
COMMENTS
Unary minus is not allowed, otherwise we would have a(n) = A091333(n).
FORMULA
A091333(n) <= a(n) <= 1 + A091333(n+1) <= 2 + A091333(n). Equality holds in the first inequality for n = 11, 17, 22, 23, 26, 29, ... .
EXAMPLE
a(5) = 6 because -5 = 1 - (1+1) * (1+1+1).
a(10) = 8 because -10 = 2 * (-5) = (1+1) * (1 - (1+1) * (1+1+1)).
CROSSREFS
Cf. A091333.
Sequence in context: A162552 A133575 A230113 * A217031 A104136 A198466
KEYWORD
nonn
AUTHOR
STATUS
approved