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%I #22 Sep 08 2022 08:44:52
%S 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,18,19,22,23,25,28,33,41,42,49,
%T 50,54,61,71
%N Numbers n such that 2^n does not contain the digit 7.
%C It is conjectured that 71 is the last term.
%t Join[{0}, Select[ Range@10000, FreeQ[ IntegerDigits[2^# ], 7] &]] (* _Shyam Sunder Gupta_, Sep 01 2007 *)
%o (Magma) [n: n in [0..1000] | not 7 in Intseq(2^n) ]; // _Vincenzo Librandi_, May 06 2015
%o (PARI) is(n)=!#select(k->k==7, Set(digits(2^n))) \\ _Charles R Greathouse IV_, May 06 2015
%Y Cf. similar sequences listed in A035064.
%K nonn,base
%O 1,3
%A _Patrick De Geest_, Nov 15 1998
%E Edited by _N. J. A. Sloane_, May 21 2008 at the suggestion of _R. J. Mathar_
%E Initial 0 added and Mathematica code adapted by _Vincenzo Librandi_, May 06 2015
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