A054039 a(n)^2 is the least square to contain n different decimal digits.

0, 4, 13, 32, 113, 322, 1017, 3206, 10124, 32043

Offset

1,2

Comments

It turns out that "...at least n..." and "...exactly n..." yield the same (and thus strictly increasing) sequence. - M. F. Hasler, Feb 02 2009

Links

Table of n, a(n) for n=1..10.

Example

13^2=169 is the first square to contain exactly 3 different digits; 322^2=103684 is the first square to contain exactly 6 different digits.

Prog

(PARI) A054039(n, k=0) = { while( #Set(Vec(Str(k^2)))<n, k++); k } /* If "exactly n" would correspond to a different sequence, this would yield some term twice in a row. The optional 2nd arg can be used to find further terms with a given # of distinct digits. - M. F. Hasler, Feb 02 2009 */

Crossrefs

Cf. A016069, A054031, A054032, A054033, A054034, A054035, A054036, A054037, A054038.

Sequence in context: A173277 A036420 A266094 * A380711 A302082 A395260

Adjacent sequences: A054036 A054037 A054038 * A054040 A054041 A054042

Keyword

nonn,fini,full,base,easy

Author

Asher Auel, Feb 28 2000

Extensions

Minor rewording, added comment, keywords "easy,full" and PARI code M. F. Hasler, Feb 02 2009

Status

approved