A316750 - OEIS

%I #12 Jul 13 2018 08:24:04

%S 1,2,4,8,16,32,46,92,841,1268,2356,1247,9442,14888,97762,955421,

%T 1910842,1234688,2346679,3345689,9876631,12235679,12344578,12456689,

%U 98743321,124466789,233457889,145667789,123355789,877654211,1755308422,8665443110,88763322100,1224456677,1233444589,2466889178

%N A self-"read and extend" sequence built following the rules visible in the Comments section.

%C Start with a(1) = 1 and a(2) = 2; read the sequence digit by digit starting from the left:

%C when the read digit is smaller than the next one, double the last integer of the sequence and extend the sequence with the result rearranged (smallest digits first and leading zeros erased);

%C when the read digit is bigger than the next one, double the last integer of the sequence and extend the sequence with the result rearranged (biggest digits first, zeros at the end);

%C when both digits are equal, double the last integer of the sequence and extend the sequence with the simple result (no rearrangement).

%H Jean-Marc Falcoz, <a href="/A316750/b316750.txt">Table of n, a(n) for n = 1..10002</a>

%e As the only digit of a(1) = 1 is smaller than 2 (the next digit), we extend the sequence with 4 (that is 2 times 2);

%e as the only digit of a(2) = 2 is smaller than 4 (the next digit), we extend the sequence with 8 (that is 2 times 4);

%e as the only digit of a(3) = 4 is smaller than 8 (the next digit), we extend the sequence with 16 (that is 2 times 8 -- with 1 coming before 6);

%e as the only digit of a(4) = 8 is bigger than 1 (the next digit), we extend the sequence with 32 (that is 2 times 16 -- with 3 coming before 2);

%e as the first digit of a(5) = 1 is smaller than 6 (the next digit), we extend the sequence with 46 (that is 2 times 32 = 64 that is rearranged in 46);

%e as the last digit of a(5) = 6 is bigger than 3 (the next digit), we extend the sequence with 92 (that is 2 times 46 = 92 rearranged in 29);

%e . . .

%e as the last digit of a(9) = 1 is equal to 1 (the next digit), we extend the sequence with 1910842 (this is simply 2 times 955421, with no rearrangement);

%e etc.

%Y Cf. A316749 (for another set of "read and extend" rules).

%K base,nonn

%O 1,2

%A _Jean-Marc Falcoz_ and _Eric Angelini_, Jul 12 2018