cp's OEIS Frontend

A316909 A self-"read and extend" sequence built following the three rules visible in the Comments section (a variation of A316765).

%I A316909 #10 Jul 16 2018 16:26:04
%S A316909 1,0,2,14,4,28,196,1372,9604,3201,1067,7469,2489,829,276,1932,644,
%T A316909 4508,3,21,7,49,5,1,0,6,42,14,4,28,196,65,455,3185,22295,7431,52017,
%U A316909 364119,121373,849611,283203,1982421,660807,220269,73423,513961,3597727,25184089,176288623,1234020361,411340120,8,56
%N A316909 A self-"read and extend" sequence built following the three rules visible in the Comments section (a variation of A316765).
%C A316909 Start with a(1) = 1 and read the sequence digit by digit starting from the left:
%C A316909 when the read digit is odd, we divide by 3 the last term of the sequence, then extend the sequence with the entire part of the result;
%C A316909 when the read digit is even (but not 0), we multiply by 7 the last term of the sequence, then extend the sequence with the result;
%C A316909 when the read digit is 0, we extend the sequence with the smallest integer not yet present in the sequence.
%C A316909 This is a possible variation among many others of the first 2 rules illustrated by A316765 (where an odd digit divides by 3 and an even digit -except 0— multiplies by 2) that shows the flexibility of the "read-and-extend" idea.
%H A316909 Jean-Marc Falcoz, <a href="/A316909/b316909.txt">Table of n, a(n) for n = 1..10001</a>
%e A316909 Reading the sequence one digit after the other, starting from the left:
%e A316909 the odd digit 1 divides 1 by three (which is 0,333...), and |0,333...| is 0;
%e A316909 the digit 0 extends the sequence with the smallest integer not present yet in the sequence, which is 2;
%e A316909 the digit 2 multiplies 2 by seven, which is 14;
%e A316909 the odd digit 1 divides 14 by three, (which is 4,666...) and |4,666...| is 4;
%e A316909 the digit 4 multiplies 4 by seven, which is 28;
%e A316909 the digit 4 multiplies 28 by seven, which is 196;
%e A316909 etc.
%Y A316909 Cf. (for more self-"read and extend" sequences) A316749, A316750, A316758, A316764 and A316765.
%K A316909 base,nonn
%O A316909 1,3
%A A316909 _Eric Angelini_ and _Jean-Marc Falcoz_, Jul 16 2018