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A225535
Numbers whose cubed digits sum to a cube, and have more than one nonzero digit.
3
168, 186, 345, 354, 435, 453, 534, 543, 618, 681, 816, 861, 1068, 1086, 1156, 1165, 1516, 1561, 1608, 1615, 1651, 1680, 1806, 1860, 3045, 3054, 3405, 3450, 3504, 3540, 4035, 4053, 4305, 4350, 4503, 4530, 5034, 5043, 5116, 5161, 5304, 5340, 5403, 5430, 5611
OFFSET
1,1
LINKS
Christian N. K. Anderson, Table of n, a(n) for n = 1..10000
EXAMPLE
5^3 + 6^3 + 1^3 + 1^3 = 343, which is 7^3.
MATHEMATICA
fQ[n_] := Module[{d = IntegerDigits[n]}, Count[d, 0] + 1 < Length[d] && IntegerQ[Total[d^3]^(1/3)]]; Select[Range[5611], fQ] (* T. D. Noe, May 19 2013 *)
PROG
(R)y=rep(0, 10000); len=0; x=0; library(gmp);
digcubesum<-function(x) sum(as.numeric(unlist(strsplit(as.character(as.bigz(x)), split="")))^3);
iscube<-function(x) ifelse(as.bigz(x)<2, T, all(table(as.numeric(factorize(x)))%%3==0));
nonzerodig<-function(x) sum(strsplit(as.character(x), split="")[[1]]!="0");
which(sapply(1:6000, function(x) nonzerodig(x)>1 & iscube(digcubesum(x))))
CROSSREFS
Cf. A225534 (cubed digits sum to a prime), A197039 (square), A046459. A055012.
Cf. A165330 (cube cycle), A046197 (cubic fixed points), A000578 (cubes).
Cf. A052034 (squared digits sum to a prime), A028839, A117685.
Cf. A164882 (n such that sum of the cubes of the digits of n^3 is perfect cube). - Zak Seidov, May 21 2013
Sequence in context: A062518 A038823 A296890 * A333874 A045242 A117529
KEYWORD
nonn,base
STATUS
approved