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 A284323 #14 Jun 25 2025 14:35:50 %S A284323 1,4,11,14,22,28,41,44,82,88,111,114,122,128,141,144,182,188,212,218, %T A284323 221,224,242,248,281,284,411,414,422,428,441,444,482,488,812,818,821, %U A284323 824,842,848,881,884,1111,1114,1122,1128,1141,1144,1182,1188,1212,1218 %N A284323 Numbers k such that product of digits of k is a power of 4. %e A284323 1111 is in the sequence because 1*1*1*1 = 1 = 4^0. %t A284323 FromDigits /@ Select[Join @@ Map[Tuples[2^Range[0, 3], #] &, Range@ 4], IntegerQ@ Log[4, Times @@ #] &] (* _Michael De Vlieger_, Mar 25 2017 *) %o A284323 (Magma) Set(Sort([n: n in [1..10000], k in [0..20] | &*Intseq(n) eq 4^k])); %Y A284323 Supersequence of A032822. %Y A284323 Cf. Numbers n such that product of digits of n is a power of k for k = 0 - 9: A284375 (k = 0), A002275 (k = 1), A028846 (k = 2), A174813 (k = 3), this sequence (k = 4), A276037 (k = 5), A276038 (k = 6), A276039 (k = 7), A284324 (k = 8), A284295 (k = 9). %K A284323 nonn,base %O A284323 0,2 %A A284323 _Jaroslav Krizek_, Mar 25 2017