

A309529


Start with a(1)=2; thereafter the sequence is always extended by adding the nth digit of the sequence to a(n) if a(n) is even, else subtracting it.


7



2, 4, 8, 16, 17, 11, 10, 17, 16, 17, 16, 16, 17, 10, 11, 5, 4, 11, 10, 16, 17, 11, 10, 17, 16, 16, 17, 16, 21, 17, 16, 17, 16, 16, 17, 11, 10, 17, 16, 17, 16, 16, 17, 10, 11, 5, 4, 10, 11, 4, 5, 1, 3, 4, 3, 10, 9, 15, 16, 9, 10, 4, 3, 9, 10
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OFFSET

1,1


COMMENTS

Among the first 10^8 terms, the last positive value occurs at n=28823742.  Lars Blomberg, Aug 10 2019


LINKS

JeanMarc Falcoz, Table of n, a(n) for n = 1..42917
Lars Blomberg, Graph of 10^8 terms
Lars Blomberg, Graph of accumulated sums of 10^8 terms


EXAMPLE

The sequence begins with 2,4,8,16,17,11,10,17,...
As a(1) = 2 (even), we have a(2) = a(1) + [the 1st digit of the seq] = 2 + 2 = 4;
as a(2) = 4 (even), we have a(3) = a(2) + [the 2nd digit of the seq] = 4 + 4 = 8;
as a(3) = 8 (even), we have a(4) = a(3) + [the 3rd digit of the seq] = 8 + 8 = 16;
as a(4) = 16 (even), we have a(5) = a(4) + [the 4th digit of the seq] = 16 + 1 = 17;
as a(5) = 17 (odd), we have a(6) = a(5)  [the 5th digit of the seq] = 17  6 = 11;
as a(6) = 11 (odd), we have a(7) = a(6)  [the 6th digit of the seq] = 11  1 = 10;
etc.


CROSSREFS

Cf. A309521 (same idea, but dealing with primes instead of even numbers).
Sequence in context: A316749 A008381 A083780 * A101466 A129851 A061681
Adjacent sequences: A309526 A309527 A309528 * A309530 A309531 A309532


KEYWORD

sign,base


AUTHOR

Eric Angelini and JeanMarc Falcoz, Aug 06 2019


STATUS

approved



