A030292 Numbers k such that k^3 has at most two different digits.

0, 1, 2, 3, 4, 7, 10, 11, 20, 100, 200, 1000, 2000, 10000, 20000, 100000, 200000, 1000000, 2000000, 10000000, 20000000, 100000000, 200000000, 1000000000, 2000000000, 10000000000, 20000000000

Offset

1,3

Comments

Except for 0, 3, 4, 7, and 11, each term is of the form 10^x or 2*10^x. - Harvey P. Dale, Feb 05 2013

Links

Table of n, a(n) for n=1..27.

Maple

filter:= n -> nops(convert(convert(n^3, base, 10), set)) <= 2:
select(filter, [$1..10^5]); # Robert Israel, Nov 10 2014

Mathematica

Join[Select[Range[0, 20], Count[DigitCount[#^3], 0]>7&], Flatten[Table[{10^n, 2*10^n}, {n, 2, 10}]]] (* Harvey P. Dale, Nov 23 2019 *)

Prog

(Python)
A030292_list, m = [0], [6, -6, 1, 0]
for n in range(1, 10**6+1):
    for i in range(3):
        m[i+1] += m[i]
    if len(set(str(m[-1]))) <= 2:
        A030292_list.append(n) # Chai Wah Wu, Nov 05 2014
(PARI) isok(n) = #Set(digits(n^3)) <= 2; \\ Michel Marcus, Nov 10 2014
(Magma) [n: n in [0..4000000] | #Set(Intseq(n^3)) le 2]; // Vincenzo Librandi, Nov 10 2014

Crossrefs

Sequence in context: A347873 A366567 A139759 * A204231 A135419 A051914

Adjacent sequences: A030289 A030290 A030291 * A030293 A030294 A030295

Keyword

nonn,base,nice

Author

Patrick De Geest

Extensions

More terms from Lior Manor, Jul 24 2001

Status

approved