This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A028845 #13 Jul 08 2025 18:54:11
%S A028845 1,4,9,11,14,19,22,27,33,39,41,72,89,91,93,98,111,114,119,122,127,133,
%T A028845 139,141,172,189,191,193,198,212,217,221,249,266,271,277,294,313,319,
%U A028845 331,333,338,346,364,379,383,391,397,411,429,436,463,492,626,634,643
%N A028845 Iterated product of digits of n is a nonzero square.
%H A028845 Harvey P. Dale, <a href="/A028845/b028845.txt">Table of n, a(n) for n = 1..1000</a>
%e A028845 E.g. 27 -> 2*7 = 14 -> 1*4 = 4 is a square.
%t A028845 ipdQ[n_]:=MemberQ[{9,4,1},NestWhile[Times@@IntegerDigits[#]&,n,#>9&]]; Select[Range[700],ipdQ] (* _Harvey P. Dale_, Apr 15 2018 *)
%Y A028845 Cf. A031347, A050626, A028837.
%K A028845 nonn,base,easy
%O A028845 1,2
%A A028845 _N. J. A. Sloane_
%E A028845 Extended (and corrected) by _Patrick De Geest_, Jun 15 1999