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A135391
Numbers n such that 9^n and 9^(n+1) have the same number of decimal digits.
1
21, 43, 65, 87, 109, 131, 152, 174, 196, 218, 240, 262, 284, 305, 327, 349, 371, 393, 415, 437, 458, 480, 502, 524, 546, 568, 590, 611, 633, 655, 677, 699, 721, 743, 764, 786, 808, 830, 852, 874, 896, 917, 939, 961, 983, 1005, 1027, 1049, 1070, 1092, 1114
OFFSET
1,1
LINKS
FORMULA
a(n)/n has the limit 1/(1-Log[9]/Log[10]) = 21.85434... - Stefan Steinerberger, Dec 12 2007
MATHEMATICA
Select[Range[1115], Length[IntegerDigits[9^# ]] == Length[IntegerDigits[9^#*9]] &] (* Stefan Steinerberger, Dec 12 2007 *)
PROG
(PARI) isok(n) = #digits(9^n) == #digits(9^(n+1)); \\ Michel Marcus, Oct 12 2016
CROSSREFS
Cf. A135358 (with 7^n).
Sequence in context: A263877 A041870 A041868 * A118569 A195049 A041874
KEYWORD
base,nonn
AUTHOR
Zak Seidov, Dec 11 2007
STATUS
approved