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A122955 Numbers k such that although the number of digits in 5^k is larger, the sum of the digits is less than that of the previous power of 5. 0
5, 11, 12, 13, 19, 25, 28, 29, 33, 35, 45, 46, 52, 53, 58, 59, 61, 62, 63, 65, 76, 78, 79, 81, 85, 88, 89, 91, 92, 95, 98, 101, 104, 108, 109, 114, 115, 116, 119, 125, 131, 136, 139, 144, 145, 158, 161, 162, 168, 169, 178, 179, 181, 184, 185, 189, 195, 197, 199, 207 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Conjecture: Natural density is log 5/log 100. - Charles R Greathouse IV, Nov 15 2010
LINKS
EXAMPLE
11 is a term because 5^11 = 48828125 has 8 digits and digit sum 4+8+8+2+8+1+2+5 = 38 while 5^10 = 9765625 has 7 digits and digit sum 9+7+6+5+6+2+5 = 40.
MATHEMATICA
Select[ Range@ 208, Floor[Log[10, 5^# ]] > Floor[Log[10, 5^(# - 1)]] && Plus @@ IntegerDigits[5^# ] < Plus @@ IntegerDigits[5^(# - 1)] &]
CROSSREFS
Cf. A066001.
Sequence in context: A244534 A034596 A166275 * A030318 A102175 A139200
KEYWORD
nonn,base
AUTHOR
Robert G. Wilson v, Oct 25 2006
STATUS
approved

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Last modified May 27 20:38 EDT 2024. Contains 372882 sequences. (Running on oeis4.)