Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #6 Jan 02 2019 03:02:39
%S 7,17,37,47,67,71,73,107,127,137,157,167,173,227,257,271,277,307,317,
%T 337,347,367,373,457,467,547,557,571,577,607,617,647,673,677,701,727,
%U 733,743,751,757,761,773,1117,1171,1217,1237,1277,1307,1327,1367
%N Primes with maximal digit = 7.
%H Robert Israel, <a href="/A106095/b106095.txt">Table of n, a(n) for n = 1..10000</a>
%p Res:= 7:
%p A:= {7}: B:= {$1..6}:
%p for d from 2 to 4 do
%p A:= {seq(seq(10*a+i,i=0..7),a=A), seq(10*b+7,b=B)}:
%p B:= {seq(seq(10*b+i,i=0..6),b=B)}:
%p Res:= Res, op(sort(convert(select(isprime,A),list)))
%p od:
%p Res; # _Robert Israel_, Jan 01 2019
%t Select[Prime[Range[200]], Max[IntegerDigits[ # ]]==7&]
%K nonn,base
%O 1,1
%A _Zak Seidov_, May 07 2005