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URL: https://oeis.org/A302599

⇱ A302599 - OEIS

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A302599
Numbers k such that digit_sum(k) > digit_sum(2k).
1
5, 6, 7, 8, 15, 16, 17, 25, 26, 35, 50, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 65, 66, 67, 68, 69, 70, 71, 75, 76, 77, 78, 79, 80, 85, 86, 87, 88, 89, 95, 96, 97, 98, 105, 106, 107, 115, 116, 125, 150, 151, 152, 155, 156, 157, 158, 159, 160, 161, 165, 166
OFFSET
1,1
COMMENTS
Conjecture: a(n) ~ 2n. - Charles R Greathouse IV, Apr 10 2018
If n is in the sequence then so is 10*n. - David A. Corneth, Apr 10 2018
a(10^9) = 2367976531. - Charles R Greathouse IV, Apr 11 2018
LINKS
EXAMPLE
17 is in this sequence because 1+7 > 3+4.
MAPLE
select(t -> convert(convert(2*t, base, 10), `+`)<convert(convert(t, base, 10), `+`), [$1..1000]); # Robert Israel, Apr 12 2018
MATHEMATICA
With[{s = Array[Total@ IntegerDigits@ # &, 332]}, Select[Range@ Floor[Length[s]/2], s[[#]] > s[[2 #]] &]] (* Michael De Vlieger, Apr 10 2018 *)
PROG
(Python)
print([y for y in range(10000) if sum([int(x) for x in str(y)]) > sum([int(z) for z in str(2*y)])])
(PARI) is(n)=sumdigits(n)>sumdigits(2*n) \\ Charles R Greathouse IV, Apr 10 2018
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved