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A240580
Numbers k such that DigitSum(5^k) > DigitSum(5^(k+1)).
1
4, 10, 11, 12, 16, 18, 24, 27, 28, 32, 34, 36, 39, 44, 45, 49, 51, 52, 57, 58, 60, 61, 62, 63, 64, 69, 75, 76, 77, 78, 80, 83, 84, 87, 88, 90, 91, 94, 96, 97, 100, 103, 106, 107, 108, 113, 114, 115, 118, 119, 124, 129, 130, 132, 135, 138, 139, 142, 143, 144, 149
OFFSET
1,1
LINKS
EXAMPLE
The digitsum(5^4) = 13 > 11 = digitsum(5^(4+1)). Hence, 4 appears in the sequence.
The digitsum(5^11) = 38 > 28 = digitsum(5^(11+1)). Hence, 11 appears in the sequence.
MAPLE
a := proc(n) local a, b, d, e; a:=5^n; b:=add( i, i = convert((a), base, 10))(a); d:=5^(n+1); e:=add( i, i = convert((d), base, 10))(d); if b > e then RETURN (n); fi; end: seq(a(n), n=1..300);
MATHEMATICA
k=Table[Total[IntegerDigits[5^n, 10]], {n, 1, 300}]; Flatten[Position[Greater@@@Partition[k, 2, 1], True]]
Select[Range[150], Total[IntegerDigits[5^#]]>Total[IntegerDigits[5^(#+1)]]&] (* Harvey P. Dale, Jun 04 2025 *)
CROSSREFS
Cf. A186775 (digitsum(2^k) > digitsum(2^(k+1))), A239935 (digitsum(3^k) > digitSum(3^(k+1))).
Sequence in context: A355497 A045855 A244216 * A102535 A074226 A106631
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, Apr 08 2014
STATUS
approved