

A309571


Start with a(1)=1; thereafter the sequence is always extended by adding the nth digit of the sequence to a(n) if both are of the same parity, otherwise subtracting it.


1



1, 2, 4, 8, 16, 15, 9, 10, 5, 14, 13, 13, 18, 17, 13, 14, 11, 12, 9, 10, 18, 17, 24, 23, 26, 25, 21, 22, 21, 22, 24, 15, 16, 16, 15, 7, 8, 1, 1, 5, 7, 4, 2, 4, 6, 1, 1, 0, 2, 4, 6, 5, 3, 1, 1, 5, 4, 9, 8, 2, 3, 9, 8, 13, 6, 2, 1, 2, 3, 4, 8, 10, 14, 20, 19, 20, 20
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OFFSET

1,2


LINKS

JeanMarc Falcoz, Table of n, a(n) for n = 1..42917


EXAMPLE

The sequence S begins with 1,2,4,8,16,15,9,10,5,...
As a(1) = 1 and the 1st digit of S are of same parity, we get a(2) = 1 + 1 = 2;
as a(2) = 2 and the 2nd digit of S are of same parity, we get a(3) = 2 + 2 = 4;
as a(3) = 4 and the 3rd digit of S are of same parity, we get a(4) = 4 + 4 = 8;
as a(4) = 8 and the 4th digit of S are of same parity, we get a(5) = 8 + 8 = 16;
as a(5) = 16 and the 5th digit of S are not of same parity, we get a(6) = 16  1 = 15;
as a(6) = 15 and the 6th digit of S are not of same parity, we get a(7) = 15  6 = 9;
as a(7) = 8 and the 7th digit of S are of same parity, we get a(8) = 9 + 1 = 10.
Etc.


CROSSREFS

This is a variant of A309529.
Sequence in context: A066005 A066600 A210025 * A210023 A301807 A062116
Adjacent sequences: A309568 A309569 A309570 * A309572 A309573 A309574


KEYWORD

sign,base


AUTHOR

Eric Angelini and JeanMarc Falcoz, Aug 08 2019


STATUS

approved



