A112321 Least n-digit number whose square is exclusionary, or 0 if no such number exists.

2, 17, 157, 1547, 15094, 203879, 0, 0, 0

Offset

1,1

Comments

m has an exclusionary square if m consists of distinct digits and m^2 is made up only of digits not appearing in m.

a(10) = 0 since 10-digit numbers either use all digits or at least one digit more than once; a(n) = 0 for n > 10 since numbers with more than 10 digits use at least one digit more than once.

References

H. Ibstedt, Solution to Problem 2623 "Exclusionary Powers", Journal of Recreational Mathematics pp. 346-9 Vol. 32 no. 4 2003-4 Baywood NY.

Links

Table of n, a(n) for n=1..9.

Crossrefs

Cf. A112322 (corresponding squares), A110815.

Sequence in context: A176934 A126037 A241135 * A362477 A276198 A178806

Adjacent sequences: A112318 A112319 A112320 * A112322 A112323 A112324

Keyword

nonn,base,fini

Author

Lekraj Beedassy and Klaus Brockhaus, Sep 08 2005

Status

approved