A260906 Numbers n such that 3*n and n^3 have the same digit sum.

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

Robert Israel, Table of n, a(n) for n = 1..320

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

Cf. A000578, A007953, A008585, A049343, A260702.

Sequence in context: A343433 A136932 A136945 * A136894 A136939 A136944

Adjacent sequences: A260903 A260904 A260905 * A260907 A260908 A260909

Keyword

nonn,base,easy

Author

Vincenzo Librandi, Nov 18 2015

Status

approved