OFFSET
1,2
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
EXAMPLE
17 is in the sequence because the square of 17 is 289 and 2*8*9 = 144 = 12^2.
MATHEMATICA
Do[a = Apply[Times, IntegerDigits[n^2]]; If[ a != 0 && IntegerQ[a^(1/2)], Print[n]], {n, 1, 10^4} ]
nzpQ[n_]:=Module[{prod=Times@@IntegerDigits[n^2]}, prod!=0 && IntegerQ[ Sqrt[ prod]]]; Select[Range[600], nzpQ] (* Harvey P. Dale, May 27 2012 *)
PROG
(PARI) ProdD(x)= { local(p=1); while (x>9 && p>0, p*=x%10; x\=10); return(p*x) } { n=0; for (m=1, 10^10, if (issquare(p=ProdD(m^2)) && p > 0, write("b066733.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Mar 20 2010
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Robert G. Wilson v, Jan 15 2002
STATUS
approved