|
%I #10 Sep 08 2022 08:45:18
%S 41,4111,11411,12211,21121,21211,22111,112121,1114111,11111141,
%T 11141111,111112121,111121121,112111211,112112111,121111121,121112111,
%U 122111111,212111111,1111111411,1111411111,11111121121,11111121211,11111211121
%N Primes with digital product = 4.
%H Vincenzo Librandi, <a href="/A107690/b107690.txt">Table of n, a(n) for n = 1..2400</a>
%t Flatten[ Table[ Select[ Sort[ FromDigits /@ Join[ Permutations[ Flatten[{4, Table[1, {n}]}]], Permutations[ Flatten[{2, 2, Table[1, {n - 1}]}] ]]], PrimeQ[ # ] &], {n, 0, 10}]]
%o (Magma) [p: p in PrimesUpTo(10^8) | &*Intseq(p) eq 4]; // _Vincenzo Librandi_, Jun 30 2017
%Y Cf. A004022, A107612, A107689, A107691, A107692, A107693, A107694, A107695, A107696, A107697, A107698.
%Y Subsequence of A199987.
%K base,nonn
%O 1,1
%A _Zak Seidov_ and _Robert G. Wilson v_, May 20 2005
|
