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Concatenating all successive absolute differences between two successive digits of a(n) produce a subchain of a(n).
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%I #7 Nov 15 2020 12:58:18

%S 10,12,20,21,24,30,36,40,42,48,50,60,63,70,80,84,90,100,120,124,200,

%T 240,248,300,360,400,421,480,500,600,700,800,842,900,1000,1200,1240,

%U 1248,2000,2400,2480,3000,3600,4000,4800,5000,6000,7000,8000,8421,9000,10000,12000,12400,12480,20000,24000,24800,30000

%N Concatenating all successive absolute differences between two successive digits of a(n) produce a subchain of a(n).

%C This is the lexicographically earliest sequence of distinct positive terms with this property.

%p a(1) = 10 is in the sequence because the absolute difference between 1 and 0 is 1, and 1 is a subchain of 10;

%p a(2) = 12 is in the sequence because the absolute difference between 1 and 2 is 1, and 1 is a subchain of 12;

%p a(3) = 20 is in the sequence because the absolute difference between 2 and 0 is 2, and 2 is a subchain of 20;

%p ...

%p a(20) = 124; the absolute difference between 1 and 2 is 1; the absolute difference between 2 and 4 is 2; concatenating those differences produce 12 and 12 is a subchain of 124; etc.

%Y Cf. A338640 [the concatenation produces a divisor of a(n)], A338641 [the starting numbers have no duplicated digits and the concatenation is a divisor of a(n)].

%K base,nonn

%O 1,1

%A _Eric Angelini_, Nov 12 2020