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A087381 Let Compri(n) be the number obtained by replacing each prime digit (2,3,5,7) of n with a '1' and a composite digit( 0,4,6,8,9) with a '0'. A 1 remains the same. a(n) = Compri(n). 1

%I #9 Jul 12 2020 13:48:06

%S 1,1,1,0,1,0,1,0,0,10,11,11,11,10,11,10,11,10,10,10,11,11,11,10,11,10,

%T 11,10,10,10,11,11,11,10,11,10,11,10,10,0,1,1,1,0,1,0,1,0,0,10,11,11,

%U 11,10,11,10,11,10,10,0,1,1,1,0,1,0,1,0,0,10,11,11,11,10,11,10,11,10,10,0

%N Let Compri(n) be the number obtained by replacing each prime digit (2,3,5,7) of n with a '1' and a composite digit( 0,4,6,8,9) with a '0'. A 1 remains the same. a(n) = Compri(n).

%C For all numbers using only composite digits (0,4,6,8,9) a(n) = 0. For a 'k' digit number using 1 and/or only prime digits a(n) = (10^k-1)/9.

%e a(4206) = 100

%e a(10235479) = 10111010

%t Join[{1},Table[FromDigits[IntegerDigits[n]/.{2->1,3->1,4->0,5->1,6->0,7->1,8->0,9->0}],{n,2,100}]] (* _Harvey P. Dale_, Jul 12 2020 *)

%Y Cf. A087380.

%K base,nonn

%O 1,10

%A _Amarnath Murthy_, Sep 09 2003

%E More terms from _David Wasserman_, May 25 2005

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)