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A260906
Numbers n such that 3*n and n^3 have the same digit sum.
2
0, 3, 6, 30, 60, 63, 126, 171, 252, 300, 324, 543, 585, 600, 630, 1260, 1281, 1710, 2520, 2925, 3000, 3240, 5430, 5850, 5946, 6000, 6300, 12600, 12606, 12633, 12810, 14631, 16263, 17100, 21618, 22308, 22971, 24663, 25200, 27633, 28845, 28887, 28965, 29241
OFFSET
1,2
COMMENTS
All terms are multiples of 3.
n is in the sequence iff 10*n is. Are there infinitely many terms not divisible by 10? - Robert Israel, Nov 20 2015
LINKS
FORMULA
A007953(A008585(a(n))) = A007953(A000578(a(n))).
EXAMPLE
126 is in the sequence because 126^3 = 2000376 and 3*126 = 378 have the same digit sum: 18.
MAPLE
select(n -> convert(convert(n^3, base, 10), `+`)=convert(convert(3*n, base, 10), `+`), 3*[$0..10^5]); # Robert Israel, Nov 20 2015
MATHEMATICA
Select[Range[0, 50000], Total[IntegerDigits[3 #]] == Total[IntegerDigits[#^3]] &]
PROG
(Magma) [n: n in [0..50000] | &+Intseq(3*n) eq &+Intseq(n^3)];
(PARI) for(n=0, 1e5, if(sumdigits(n^3)==sumdigits(3*n), print1(n, ", "))) \\ Altug Alkan, Nov 20 2015
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Vincenzo Librandi, Nov 18 2015
STATUS
approved