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A028845
Iterated product of digits of n is a nonzero square.
4
1, 4, 9, 11, 14, 19, 22, 27, 33, 39, 41, 72, 89, 91, 93, 98, 111, 114, 119, 122, 127, 133, 139, 141, 172, 189, 191, 193, 198, 212, 217, 221, 249, 266, 271, 277, 294, 313, 319, 331, 333, 338, 346, 364, 379, 383, 391, 397, 411, 429, 436, 463, 492, 626, 634, 643
OFFSET
1,2
LINKS
EXAMPLE
E.g. 27 -> 2*7 = 14 -> 1*4 = 4 is a square.
MATHEMATICA
ipdQ[n_]:=MemberQ[{9, 4, 1}, NestWhile[Times@@IntegerDigits[#]&, n, #>9&]]; Select[Range[700], ipdQ] (* Harvey P. Dale, Apr 15 2018 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
Extended (and corrected) by Patrick De Geest, Jun 15 1999
STATUS
approved