OFFSET
1,2
REFERENCES
Michael Huke, Solution to exercise psi-15 (German language article), WURZEL 11/2016, November 2016, page 252, http://wurzel.org/
EXAMPLE
For n=3, a(3)=661: q(661)^2 = (6*6*1)^2 = 36^2 = 1296 = 4*3*6*9*2*1 = q(436921) = q(661^2).
MATHEMATICA
Select[Range[1, 10^6, 2], And[MatchQ @@ #, Times @@ # != 0] &@{(Times @@ IntegerDigits@ #)^2, Times @@ IntegerDigits[#^2]} &] (* Michael De Vlieger, Dec 06 2016 *)
PROG
(PARI) pd(n) = my(d=digits(n)); prod(k=1, #d, d[k]);
isok(n) = (n % 2) && (p = pd(n)^2) && (p == pd(n^2)); \\ Michel Marcus, Dec 04 2016
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Volker Diels-Grabsch, Nov 18 2016
EXTENSIONS
More terms from Jon E. Schoenfield, Dec 02 2016
STATUS
approved