OFFSET
1,1
COMMENTS
The first digit of a term is either 7, 8 or 9 and the last digit is either 5, 6 or 7. Conjecture: no term is a multiple of 5. - Chai Wah Wu, Sep 10 2017
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..1224 (n = 1..326 from Hiroaki Yamanouchi).
MATHEMATICA
fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {1, 4}] == 0, Last@ c == 0, c[[5]] > 0, c[[9]] > 0]]; Select[Range@ 10000000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, May 05 2015 *)
PROG
(PARI) is(n) = vecmin(digits(n))==5 && vecmin(digits(n^2))==5 && vecmax(digits(n))==9 && vecmax(digits(n^2))==9
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Felix Fröhlich, May 03 2015
EXTENSIONS
a(14)-a(21) from Hiroaki Yamanouchi, May 07 2015
STATUS
approved