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A195908 Powers of 7 which have no zero in their decimal expansion.

%I A195908 #28 Jan 28 2023 14:01:04
%S A195908 1,7,49,343,117649,823543,282475249,1977326743,11398895185373143,
%T A195908 378818692265664781682717625943
%N A195908 Powers of 7 which have no zero in their decimal expansion.
%C A195908 Probably finite. Is 378818692265664781682717625943 the largest term?
%C A195908 No further terms up to 7^50,000, a number with 42,255 digits. - _Harvey P. Dale_, Jul 14 2022
%H A195908 M. F. Hasler, <a href="https://oeis.org/wiki/Zeroless_powers">Zeroless powers</a>, OEIS Wiki, Mar 07 2014
%H A195908 C. Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_607.htm">Puzzle 607. A zeroless Prime power</a>, on primepuzzles.net, Sept. 24, 2011.
%H A195908 W. Schneider, <a href="http://oeis.org/A007496/a007496.html">NoZeros: Powers n^k without Digit Zero</a> (local copy of www.wschnei.de/digit-related-numbers/nozeros.html), as of Jan 30 2003.
%F A195908 a(n) = 7^A030703(n).
%F A195908 A000420 intersect A052382.
%t A195908 Select[7^Range[0,50],DigitCount[#,10,0]==0&] (* _Harvey P. Dale_, Jul 14 2022 *)
%o A195908 (PARI) for( n=1,9999, is_A052382(7^n) && print1(7^n,","))
%o A195908 (Magma) [7^n: n in [0..3*10^4] | not 0 in Intseq(7^n)]; // _Bruno Berselli_, Sep 26 2011
%Y A195908 Cf. A195942, A195943, A195944, A195945, A195946, A195948, A007377, A008839, A030700, A030701, A030702, A030703, A030704, A030705, A030706.
%K A195908 nonn,base
%O A195908 1,2
%A A195908 _M. F. Hasler_, Sep 25 2011
%E A195908 Keyword:fini removed by _Jianing Song_, Jan 28 2023 as finiteness is only conjectured.