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A004221
a(n) = ceiling(10*log_10(n)).
3
0, 4, 5, 7, 7, 8, 9, 10, 10, 10, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18
OFFSET
1,2
MATHEMATICA
Ceiling[10*Log[10, Range[60]]] (* Harvey P. Dale, Apr 21 2013 *)
CROSSREFS
Sequence in context: A151551 A021690 A109896 * A239504 A033557 A259600
KEYWORD
nonn
STATUS
approved