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A236077 Cubes which remain (integer) cubes when divided by their digital sum. 1
1, 8, 512, 1000, 8000, 19683, 35937, 46656, 59319, 74088, 125000, 157464, 185193, 328509, 373248, 421875, 474552, 512000, 592704, 658503, 804357, 1000000, 1157625, 1259712, 1331000, 1367631, 1481544, 2460375, 2628072 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 100 terms from Bajpai)
EXAMPLE
19683 is in the sequence because 19683 divided by its digital sum (1+9+6+8+3 = 27) gives 729 which is also a cube: 729 = 9^3.
46656 is in the sequence because 46656 divided by its digital sum (4+6+6+5+6 = 27) gives 1728 which is also a cube: 1728 = 12^3.
MAPLE
with(StringTools):KD := proc() local a, b, d, e; a:=n^3; b:=add( i, i = convert((a), base, 10))(a); d:=a/b; e:=evalf(d^(1/3)); if e=floor(e) then RETURN (a); fi; end: seq(KD(), n=1..200);
PROG
(PARI)
digsum(n) = d=eval(Vec(Str(n))); sum(i=1, #d, d[i])
s=[]; for(n=1, 200, d=digsum(n^3); if(n^3%d==0 && ispower(n^3\d, 3), s=concat(s, n^3))); s \\ Colin Barker, Jan 22 2014
CROSSREFS
Intersection of A005349 and A053058.
Cf. A000578 (cubes), A007953 (digital sum).
Sequence in context: A281136 A228292 A082385 * A061460 A016935 A241756
KEYWORD
base,nonn
AUTHOR
K. D. Bajpai, Jan 19 2014
STATUS
approved

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Last modified July 20 19:14 EDT 2024. Contains 374459 sequences. (Running on oeis4.)