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Largest Brady number with n digits.
0

%I #11 Dec 10 2019 23:29:27

%S 6569,73857,818996,9082813,62254526,690413273,7656800529,84915219092,

%T 941724210541,6454673763134,71583428964617,793872392373921,

%U 8804179745077748,97639849588229149,669233485047004862,7421913081219006521,82310277378456076593,912834964244235849044

%N Largest Brady number with n digits.

%C If a(n) = A247698(k), then a(n+1) = A247698(k+4) or a(n+1) = A247698(k+5). - _Charles R Greathouse IV_, Dec 10 2019

%H Brady Haran and Matt Parker, <a href="https://www.youtube.com/watch?v=D8ntDpBm6Ok"> Brady Numbers</a>, Numberphile video (2014).

%t b[1] = 2308; b[2] = 4261; b[n_] := b[n] = b[n-1] + b[n-2]; a[n_] := Block[ {k=1}, While[ IntegerLength[b@k] <= n, k++]; b[k-1]]; a /@ Range[4, 21] (* _Giovanni Resta_, Sep 24 2018 *)

%Y Cf. A247698, A247839.

%K nonn,base,easy

%O 4,1

%A _Joshua Oliver_, Sep 24 2018