A067070 Cubes whose product of digits is a cube > 0.
1, 8, 24389, 226981, 9393931, 11239424, 17373979, 36264691, 66923416, 94818816, 348913664, 435519512, 463684824, 549353259, 555412248, 743677416, 3929352552, 4982686912, 5526456832, 11329982936, 12374478297, 12681938368, 15142552424
Offset: 1
Examples
24389 is in the sequence because (1) it is a cube and (2) the product of its digits is 2*4*3*8*9, = 1728 which is a cube > 0.
References
- Felice Russo, A set of new Smarandache Functions, Sequences and conjectures in number theory, American Research Press, Lupton USA.
Links
- David A. Corneth, Table of n, a(n) for n = 1..10000 (first 1000 terms from Harry J. Smith)
Programs
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Mathematica
pdcQ[n_]:=Module[{pd=Times@@IntegerDigits[n]},pd>0&&IntegerQ[ Surd[ pd,3]]]; Select[Range[3000]^3,pdcQ] (* Harvey P. Dale, Jun 01 2015 *)
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PARI
isA237767(k)={my(p=vecprod(digits(k))); p && ispower(p,3)} { for (m=1, 2500, if(isA237767(m^3), print1(m^3, ", "))) } \\ Harry J. Smith, May 04 2010
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PARI
first(n) = { my(res = List(), c, vp, i); for(i = 1, oo, c = i^3; vp = vecprod(digits(c)); if(vp && ispower(vp,3), listput(res, c); if(#res >= n, return(Vec(res)) ) ) ) } \\ David A. Corneth, Dec 01 2023
Formula
a(n) = A067071(n)^3. - Andrew Howroyd, Dec 05 2024
Extensions
More terms from Sascha Kurz, Mar 23 2002
One further term from Luc Stevens (lms022(AT)yahoo.com), May 03 2006
Edited by R. J. Mathar, Aug 08 2008
Offset changed from 0 to 1 by Harry J. Smith, May 04 2010
Comments